docs: add dedicated Dify onboarding and usage guide

[acedatacloud-dev]

Summary

Adds dedicated Chinese and English Dify onboarding guides with the available official OpenAI-compatible provider path and a separately labeled Ace Data Cloud Provider submission path. Covers API-key scope, current/older Dify navigation, the first LLM workflow, tools/images, usage reconciliation and troubleshooting.

This supersedes only the Dify pages and Dify navigation entry in draft #109. It changes three files, from current main 144babe5; it does not include n8n, GitLab or Open WebUI work. Backend guide correction https://github.com/AceDataCloud/PlatformBackend/pull/2109 is already merged.

Validation

• npm test: 48 Python and 4 MDX tests passed.
• Both new MDX pages passed syntax and local-link validation.
• python3 scripts/validate_nav.py: passed.
• Mintlify 4.2.970 broken-links: no broken links.
• Mintlify local preview served both new pages with HTTP 200 and their expected headings. Full browser visual QA is not claimed.
• Existing Provider evidence: packaged CLI real request, stream/tool round trip, official package/serverless installation tests; read-only reconciliation found the exact DIFY_PACKAGE_OK request and its nonzero Credit deduction. No billable request was repeated for these docs.

Publication and coordination

Dify Marketplace PR langgenius/dify-plugins#3219 remains open; first-contributor CI needs maintainer approval and Marketplace version readback still says not found. These guides do not claim default installation or completed CE/Cloud UI E2E. Attempts to download the official Dify CE image failed at Docker Hub authentication/registry with EOF.

This PR can merge independently. For parallel integration PRs, retain one Integrations group per language and append each platform's page once. Keep #109 draft or close it after its other platform-specific successors are ready; do not merge its stale Dify pages over these expanded guides. No production sync or deployment was performed. Prepared with AI assistance; no separate adversarial review was requested.

CE workflow validation (2026-10-07)

CE validation update (2026-10-07): the official Dify 1.17.1 API/Web images and plugin daemon 0.6.10-local now run in an isolated local environment. The submitted package's source was connected through Dify's official remote-debug flow, with signature verification left enabled.

Using Dify's console APIs, the provider appeared in the model-provider summary, saving gpt-4.1-mini credentials returned HTTP 201, and the model was listed as active. A real Start → LLM → Output workflow then completed all three nodes and returned DIFY_CE_20261007_OK (17 prompt tokens, 25 completion tokens, 42 total). The workflow run ID is 5d0fb628-c8ae-4d11-bd04-e1f844868c62.

The provider icon served by Dify matches the official PNG SHA-256 3e2c6e2d1a61a549dae2374ec4444c77f4c2617c8f3772bdd4cd6e52bf20767e. This adds real CE workflow-engine coverage to the earlier SDK/CLI checks. It is remote-debug installation and console-API validation; Marketplace installation, Dify Cloud and browser UI interaction remain unverified. No product behavior or package bytes changed in this check.