feat: generate per-package contract docs, aligned with docs/code/ convention

[ntlaletsi70]

Summary

• Adds `mage docs`, which generates Markdown documentation from `.proto` comments via `protoc-gen-doc`, driven by `buf` — one file per proto package directory (`docs/code/blanketops/.md`), matching exactly the `docs/code/` layout `gomarkdoc` produces in the sibling `environments` and `environments-controller` repos.
• Wired into `finalize-release.yml` only, right after the existing Go/TS codegen step — this repo already generates and commits its Go/TS contracts exclusively at release time (no async on-push-to-main job), which is the correct, race-free pattern the sibling repos' docs generation had to be retrofitted into after hitting a real develop/main drift bug this session. Docs generation follows that same already-correct shape from the start — no new race introduced.
• Cleaned up banner-divider comments (`// ====...====`) in 11 `.proto` files first — `protoc-gen-doc` attaches a message/service's leading comment block the same way Go's doc tooling does (no blank line before the declaration), so an attached banner would have rendered as literal ASCII dashes in the generated docs, the same failure mode already fixed across the Go repos this session. Verified with `buf lint` and `buf build` that the comment-only edits didn't break anything, and spot-checked the generated output renders clean.
• Includes the initial generated `docs/` output so docs exist immediately rather than waiting for the next release cut.

Test plan

• `buf lint` / `buf build` clean after the banner cleanup
• `go build ./...` clean
• `mage lint` passes
• `mage docs` generates cleanly, output spot-checked (e.g. `Route` message renders "Resource" as its description, no ASCII dashes)
• Exercise `mage docs` as part of a real `finalize-release.yml` run