[Two-Play]

Refs #43. Replaces #44: instead of only a hint, the app can now start the work on the server itself.

What

• Settings → Server tasks (new page, also linked as "Check previews on the server" under the preview settings):
  • Scan library (sheet: what to create for new files), Generate (covers, MP4 and WebP previews, sprites, marker previews/screenshots, phashes; only what's missing), Auto tag, Clean (with confirmation).
  • Running tasks from Stash's jobQueue, polled every 2 s while the page is open, with progress and a stop button.
  • Preview check: fetches one byte of the WebP/MP4 preview URLs of 8 random scenes and 4 markers (Stash answers 404 for missing files). If the WebP previews are missing: an explanation and "Generate animated previews". Runs again when a job finishes.
• Preview format (Settings → Scene cards): animated image (WebP, default) or video (MP4). Video plays Stash's MP4 preview in its own muted media_kit player (PreviewVideo), one at a time, and the settings show a hint about the extra data, battery and memory. Markers keep the WebP.
• GraphQL: tasks.graphql (jobQueue, stopJob, metadataScan/Generate/AutoTag/Clean). The demo accepts the mutations and has an empty queue.
• Backlog: 3.4 ✅, 13.16 updated, new 13.18. CLAUDE.md updated.

Checks

• dart analyze: no issues
• flutter test: all 352 pass (new server_tasks_test.dart, demo test for the tasks and the check)
• Not tried on a device against a real Stash yet, in particular the MP4 preview player's performance.

🤖 Generated with Claude Code

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 107 duplication

Metric	Results
Duplication	107

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