sync: add kling API documentation

[Copilot]

The kling service was updated in the upstream Docs repo but had no corresponding subdirectory in this monorepo.

Changes

• kling/README.md — Service overview with quick start, API table linking all three endpoints, and resource links
• kling/docs/kling_videos_generation_api_integration_guide.md — Videos API guide covering text-to-video, image-to-video, and extend actions; includes full model capability matrix (kling-v1 → kling-video-o1) with per-model support for end_image_url, generate_audio, camera_control, and 4k mode
• kling/docs/kling_tasks_api_integration_guide.md — Tasks API guide with single and batch retrieve examples and full response schema
• kling/docs/kling_motion_generation_api_integration_guide.md — Motion transfer API guide (/kling/motion) covering image_url + video_url input, character_orientation, and async callback

All guides translated from the Chinese MDX source in AceDataCloud/Docs to English Markdown, following the same conventions as existing services (e.g. wan/).

[acedatacloud-dev]

Auto-closed during PR backlog cleanup: superseded sync (+733/-0) — content covered by next dispatch against current Docs. Root cause was a broken auto-merge in sync-from-docs.yml (now fixed in PR #143). The fix lands a pre-cleanup step + reliable completion signal so future dispatches will not leak PRs. If this PR contained content not yet in main, the next docs-updated dispatch will re-create it via the working pipeline.