fix: allow multi-segment paths in userdata API routes

[Peuqui]

Summary

• Change aiohttp route parameters from {file} to {file:.*} in all /userdata/ routes to allow paths containing slashes (e.g. workflows/my-workflow.json)
• The {file} parameter only matches a single path segment in aiohttp, causing 404 errors when requesting files in subdirectories without URL-encoding the slash
• While the frontend uses encodeURIComponent as a workaround, this fix ensures routes work correctly with both encoded and unencoded paths

Problem

Requests to /userdata/workflows/filename.json return 404 because aiohttp's {file} route parameter only captures a single path segment (workflows), not the full path (workflows/filename.json).

The existing parse.unquote() workaround (from PR #4801) only helps when the frontend URL-encodes the slash as %2F. External API consumers and some frontend code paths that construct URLs with literal slashes are affected.

Changes

app/user_manager.py — 4 route definitions updated:

Route	Before	After
GET	/userdata/{file}	/userdata/{file:.*}
POST	/userdata/{file}	/userdata/{file:.*}
DELETE	/userdata/{file}	/userdata/{file:.*}
POST (move)	/userdata/{file}/move/{dest}	/userdata/{file:.*}/move/{dest:.*}

Test plan

• Verify GET /userdata/workflows/test.json returns 200 (was 404)
• Verify GET /userdata/workflows%2Ftest.json still works (backward compatible)
• Verify workflow sidebar loading works for files in subdirectories
• Verify saving workflows to subdirectories works
• Verify file move/rename still works

Closes #10151

[comfy-pr-bot]

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