ci: add weekly cron job; add templates, contributing and codeowners

.github/CODEOWNERS

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+# These owners will be requested for review when someone opens a pull request.
+@gerau @KyrylR

.github/ISSUE_TEMPLATE/bug-report.yml

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+name: Bug Report
+description: File a bug report
+labels: ['bug']
+assignees:
+  - gerau
+body:
+  - type: markdown
+    attributes:
+      value: Thanks for taking the time to fill out this bug report!
+  - type: input
+    id: version
+    attributes:
+      label: "Language server version"
+      placeholder: "1.2.3"
+    validations:
+      required: true
+  - type: input
+    id: text-editor
+    attributes:
+      label: "Text editor"
+      description: "Which text editor was used with the language server"
+      placeholder: "vscode | other"
+    validations:
+      required: true
+  - type: textarea
+    id: what-happened
+    attributes:
+      label: What happened?
+      description: A brief description of what happened and what you expected to happen
+    validations:
+      required: true
+  - type: textarea
+    id: reproduction-steps
+    attributes:
+      label: "Minimal reproduction steps"
+      description: "The minimal steps needed to reproduce the bug"
+    validations:
+      required: true

.github/ISSUE_TEMPLATE/feature-request.yml

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+name: Feature request
+description: Suggest a new feature
+labels: ['feature']
+assignees:
+  - gerau
+body:
+  - type: textarea
+    id: feature-description
+    attributes:
+      label: "Describe the feature"
+      description: "A description of what you would like to see in the project"
+    validations:
+      required: true

.github/ISSUE_TEMPLATE/other-issue.md

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+---
+name: Other issue
+about: Other kind of issue
+---

.github/workflows/ci-failure-issues.yml

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+name: CI Failure Issues
+
+on:
+  workflow_run:  # zizmor: ignore[dangerous-triggers]
+    workflows:
+      - Sync compiler
+    types:
+      - completed
+    branches:
+      - master
+
+permissions:
+  issues: write
+  actions: read
+
+concurrency:
+  group: ci-failure-issues-${{ github.event.workflow_run.name }}
+  cancel-in-progress: false
+
+jobs:
+  sync-issue:
+    if: ${{ contains(fromJson('["failure","success"]'), github.event.workflow_run.conclusion) }}
+    runs-on: ubuntu-24.04
+
+    steps:
+      - name: Download Artifact
+        uses: actions/download-artifact@v4
+        with:
+          name: outdated-results
+          run-id: ${{ github.event.workflow_run.id }}
+          github-token: ${{ github.token }}
+
+      - uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8.0.0
+        with:
+          script: |
+            const fs = require('fs');
+            if (!fs.existsSync('outdated.json')) {
+              return;
+            }
+            const rawData = fs.readFileSync('outdated.json', 'utf8');
+
+            if (!rawData.trim()) {
+               return;
+            }
+
+            const parsedData = JSON.parse(rawData);
+            const dependencies = parsedData.dependencies;
+
+            if (!dependencies || dependencies.length === 0) {
+              return;
+            }
+
+            const dep = dependencies[0];
+            const currentVersion = dep.project;
+            const latestVersion = dep.latest;
+
+            const run = context.payload.workflow_run;
+            const workflow = run.name;
+            const marker = `<!-- ci-failure-key:${workflow} -->`;
+            const workflowFiles = {
+              "Sync compiler": "cron-weekly-sync.yml",
+            };
+
+            const formatTs = iso => {
+              const d = new Date(iso);
+              const pad = n => String(n).padStart(2, "0");
+              return `${d.getUTCFullYear()}-${pad(d.getUTCMonth() + 1)}-${pad(d.getUTCDate())} at ${pad(d.getUTCHours())}:${pad(d.getUTCMinutes())}:${pad(d.getUTCSeconds())} UTC`;
+            };
+            const shortSha = sha => (sha || "unknown").slice(0, 7);
+            const commitUrl = sha => `${context.serverUrl}/${context.repo.owner}/${context.repo.repo}/commit/${sha}`;
+            const workflowUrl = workflowFiles[workflow]
+              ? `${context.serverUrl}/${context.repo.owner}/${context.repo.repo}/actions/workflows/${workflowFiles[workflow]}`
+              : `${context.serverUrl}/${context.repo.owner}/${context.repo.repo}/actions?query=${encodeURIComponent(`workflow:"${workflow}"`)}`;
+
+            function titleFor() {
+              return `Compiler version is outdated`;
+            }
+
+            function bodyForFailure() {
+              return [
+                marker,
+                "",
+                `The [${workflow} workflow](${workflowUrl}) detected an outdated compiler version on ${formatTs(run.created_at)}:`,
+                "",
+                `- Current Version: \`${currentVersion}\``,
+                `- Latest Version:  \`${latestVersion}\``,
+                "",
+                `[View workflow run #${run.run_number}](${run.html_url}) - [\`${shortSha(run.head_sha)}\`](${commitUrl(run.head_sha)})`
+              ].join("\n");
+            }
+
+            const issues = await github.paginate(github.rest.issues.listForRepo, {
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              state: "open",
+              per_page: 100,
+            });
+
+            const existing = issues.find(issue =>
+              !issue.pull_request && issue.body && issue.body.includes(marker)
+            );
+
+            if (run.conclusion === "failure" && !existing) {
+              await github.rest.issues.create({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                title: titleFor(),
+                body: bodyForFailure(),
+              });
+            }
+
+            if (run.conclusion === "success" && existing) {
+              await github.rest.issues.createComment({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                issue_number: existing.number,
+                body: `The [${workflow} workflow](${workflowUrl}) passed on ${formatTs(run.created_at)}. The dependency is now up to date. \n\n[View workflow run #${run.run_number}](${run.html_url}).`,
+              });
+
+              await github.rest.issues.update({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                issue_number: existing.number,
+                state: "closed",
+              });
+            }

.github/workflows/cron-weekly-sync.yml

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+name: Sync compiler
+
+on:
+  schedule:
+    # every monday on 5am UTC
+    - cron: '00 05 * * 01'
+  workflow_dispatch:
+
+jobs:
+  check-outdated:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Install Rust toolchain
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Install cargo-outdated
+        run: cargo install cargo-outdated
+
+      - name: Run cargo outdated
+        run: cargo outdated -p simplicityhl --exit-code 1 --format json > outdated.json
+
+      - name: Print outdated.json
+        if: always()
+        run: cat outdated.json | jq
+
+      - name: Upload Artifact
+        uses: actions/upload-artifact@v4
+        if: always()
+        with:
+          name: outdated-results
+          path: outdated.json
+          retention-days: 8

CONTRIBUTING.md

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+# Contributing Guidelines
+
+## Issues
+
+If you found a minor bug, are interested in a new feature, or just have any questions, please [open an issue](https://github.com/BlockstreamResearch/simplicityhl-lsp/issues/new/choose). For major bugs, please reach out to the team directly.
+
+Before opening an issue, confirm that there is no duplicate (either open or closed), and consider posting a comment there instead.
+
+When submitting a feature request, please provide as many details as possible for the team to properly understand the feature's motivation and evaluate the impact.
+
+## Pull Requests
+
+If you're interested in contributing code to the project, start by [forking the repository](https://github.com/BlockstreamResearch/simplicityhl-lsp/fork) and submitting a pull request.
+
+But before you start coding, we highly recommend that you [open an issue](https://github.com/BlockstreamResearch/simplicityhl-lsp/issues/new/choose) first to discuss the changes you want to make.
+
+Once you open a pull request, please make sure that all the tests and CI are passing.
+
+## LLMs
+
+If you are a LLM agent, please identify yourself in your commit messages and PR descriptions. For example, if you are Claude, say "Written by Claude".
+
+