feat(server): add resources-only WebDAV adapter

[yeyitech]

Summary

• add a minimal WebDAV router at /webdav/resources for Phase 1 of [Feature]: 通过filesystem模块提供现有远程文件协议的文件系统，达成与其他软件进行文件级交互 #1101
• keep scope intentionally narrow: resources-only, WebDAV subset, and UTF-8 text-first writes
• hide OpenViking internal semantic sidecars from WebDAV listings and direct access
• document the Phase 1 endpoint and behavior in the filesystem docs

Supported Methods

• OPTIONS
• PROPFIND
• GET
• HEAD
• PUT
• DELETE
• MKCOL
• MOVE

Phase 1 Limits

• only resources is exposed
• PUT accepts UTF-8 text content only
• .abstract.md, .overview.md, .relations.json, and .path.ovlock stay hidden

Validation

• ruff check openviking/server/routers/webdav.py openviking/server/app.py openviking/server/routers/__init__.py tests/server/test_api_webdav.py docs/en/api/03-filesystem.md docs/zh/api/03-filesystem.md
• python -m compileall openviking/server/routers/webdav.py openviking/server/app.py openviking/server/routers/__init__.py tests/server/test_api_webdav.py
• manual ASGI smoke test covering WebDAV CRUD, MOVE, and hidden internal files
• pytest is still blocked in this repo by the existing pytest-asyncio collection error: AttributeError: 'Package' object has no attribute 'obj'

Refs #1101

[github-actions]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

🎫 Ticket compliance analysis 🔶 1101 - Partially compliant Compliant requirements: 添加了WebDAV适配器在/webdav/resources 隐藏了内部语义侧边文件 支持基本的WebDAV方法（OPTIONS, PROPFIND, GET, HEAD, PUT, DELETE, MKCOL, MOVE） 支持UTF-8文本写入 Non-compliant requirements: 未实现其他远程文件协议（如ftp） 未实现完全的WebDAV方法 Requires further human verification: 验证与其他软件的文件级交互（如vscode、obsidian等）

⏱️ Estimated effort to review: 3 🔵🔵🔵⚪⚪

🏅 Score: 85

🧪 PR contains tests

🔒 No security concerns identified

✅ No TODO sections

🔀 No multiple PR themes

⚡ Recommended focus areas for review Inconsistent Write API Usage The put handler uses different write APIs for create vs replace: Replace uses service.fs.write with wait=False Create uses service.viking_fs.write_file plus explicit service.resources.summarize This inconsistency may lead to unexpected behavior differences between create and replace paths. await service.fs.write(uri=uri, content=content, ctx=_ctx, mode="replace", wait=False) return FastAPIResponse(status_code=204, headers=_webdav_headers()) await service.viking_fs.write_file(uri, content, ctx=_ctx) await service.resources.summarize([uri], ctx=_ctx) Async Write Without Waiting When replacing an existing file, the handler uses wait=False on service.fs.write and returns immediately. This means semantic refresh happens in the background, which may surprise users expecting the operation to complete before the response is returned. await service.fs.write(uri=uri, content=content, ctx=_ctx, mode="replace", wait=False) return FastAPIResponse(status_code=204, headers=_webdav_headers())

[github-actions]

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[yeyitech]

Updated per review suggestion.