docs: add n8n, Dify, GitLab, and Open WebUI onboarding

[acedatacloud-dev]

Summary

• Add Chinese and English onboarding guides for n8n, Dify, GitLab CI, and Open WebUI.
• Include an importable n8n chat workflow and a manual GitLab pipeline example. Credentials remain in n8n/Open WebUI/Dify or GitLab CI settings.
• Use Dify's official OpenAI-compatible model provider and AceDataCloud's verified /v1 chat route. The stale Backend Dify guide and retired-plugin claims were corrected in merged PlatformBackend #2109.

Validation

• npm test: 48 Python tests and 4 MDX tests passed. All eight new MDX pages passed syntax and local-link validation; navigation entries resolve.
• n8n workflow JSON was parsed and its body expression evaluated by the real n8n-workflow@2.16.0 Expression engine. Parameters and node versions were cross-checked against n8n 2.41.3 source. Bearer credential is native; chat POST redirects are disabled.
• GitLab YAML parsed, and the script passed sh -n.
• An unauthenticated POST to /v1/chat/completions reached the token gate. The old /openai/v1/chat/completions path returned 404. No billable call was made.

Publication and limits

• After merge, verify Mintlify deployment and both raw example URLs. A full n8n UI import, Open WebUI chat, and GitLab CI run remain unverified because the platform images could not be downloaded and no valid AceDataCloud token was used.
• This PR does not submit a template to n8n's library or publish a GitLab CI/CD Catalog component. Dify uses its existing Marketplace provider; it does not restore retired first-party plugins.

[acedatacloud-dev]

Follow-up POC: added Chinese and English Open WebUI setup pages in 3d782cc. The pages use Open WebUI's native OpenAI-compatible connection with https://api.acedata.cloud/v1, document manual Model IDs if /models verification fails, and passed MDX syntax/local-link checks. A live Open WebUI chat was not run because it would require a billable AceDataCloud token; this remains a protocol/configuration POC.

[acedatacloud-dev]

POC verification update: the imported workflow JSON was evaluated with n8n-workflow@2.16.0's real Expression engine. The Edit Fields output resolved to model=gpt-5.5 and the expected prompt; the HTTP node's JSON body resolved to the expected non-streaming Chat Completions request. The node configuration was cross-checked against n8n 2.41.3 source: Set node 3.4, HTTP Request 4.3, native Bearer Auth, JSON body, and disabled POST redirects. Full n8n UI import and a billable first call remain unverified because the image/package downloads did not complete and no API token was used.

[acedatacloud-dev]

The user asked to track and deliver each ecosystem in its own chat and PR. I converted this mixed Docs PR to draft while the n8n, Dify, GitLab, and Open WebUI owners extract their respective pages/examples into dedicated PRs from the current base. Please do not merge #109 as the final release. It remains a reviewable source of the already completed work until each platform PR preserves its relevant content; then this mixed PR can be closed without losing work.

[acedatacloud-dev]

All platform content from this mixed draft has dedicated PRs: Dify #110, GitLab #111, Open WebUI #112, and n8n #113. Each PR includes its own navigation entry and relevant guide/example; the dedicated PRs now contain further platform-specific validation and fixes. Closing this superseded mixed draft to keep review and release tracking per platform. No work is deleted; the branch and commit remain recoverable.