Add full-screen image browsing to the dashboard

[FlintSH]

What does your PR do?

Adds full-screen image browsing directly to the existing dashboard file grid. Open an image thumbnail, then browse with previous/next buttons, arrow keys, or a mobile swipe—even across result pages. Fit, actual size, zoom, pan, and download controls live inside the viewer.

Use the existing file-type filter to narrow the grid to images. Optional week/month/year grouping lives inside the Upload date menu. Share pages get one small expand button to open the same viewer.

Why are you making these changes?

Implements the phone-gallery workflow clarified in #183: a grid of images, full-image viewing, and quick navigation. Upload-date grouping provides the requested categorization.

How did you implement it?

• Reuses the existing authenticated image and download routes. Share links expand only their authorized image.
• Preserves the existing search, file-type, visibility, date, and sort filters while browsing. Image navigation uses the current image as an anchor with deterministic ordering, so uploads and deletions cannot shift a page boundary into a duplicate or skipped image. Grouping uses upload dates and chronological sort.
• Image thumbnails open the gallery; the card menu and modified link clicks still open the file page.
• Uses a focus-trapped dialog with Escape/return-focus behavior, keyboard zoom and panning, mobile swipe navigation, and recoverable loading/error states.
• Background library updates preserve the current image and zoom; the next navigation refreshes its neighbors. Closing restores focus, with a library-heading fallback if the original file leaves the results. Changing date grouping starts at page one.

Screenshots / Recordings (if UI)

Existing file grid, filtered to JPEG images and grouped by upload month:

Full-screen viewing with compact controls:

Actual size, mobile, and share page

Zoom and pan for image details:

Mobile viewer with swipe navigation:

A single expand control on share pages:

Related Issues

Closes #183.

Additional Info

• Greptile review: 5/5 on 4f44f36, with no outstanding blocking issues.
• GitHub test suite: 480 passed, 1 skipped, including database-backed tests. Build, TypeScript, ESLint, and formatting checks pass on 4f44f36.
• Anchored API tests cover sorting and ties in both directions, owner/filter scoping, removed images, and exact position counts. Thirteen hook regression tests cover refreshes, shifted boundaries, and request cancellation. Five additional database-backed browser scenarios confirm insertions/deletions before the active image preserve exact next/previous neighbors on both the first and later viewer pages, with correct end controls. Browser validation also covers background refresh with zoom, focus restoration when the opener disappears, grouping changes from page two, the existing file-type filter, navigation across filtered and mixed-file pages, Back restoration, reset, and 320px/390px layouts. The viewer also passed zoom/pan/swipe, focus/scroll restoration, failed-image recovery, and protected-link checks.
• Meticulous could not create a cloud run: the image build, smoke test, and upload succeeded, then the service rejected test creation because this project hit its plan limit. No cloud visual verdict is available. CI log.

Screenshots use disposable local fixtures with public sample photos from Lorem Picsum.

[github-actions]

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Commit: 4f44f3687451

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[greptile-apps]

Greptile Summary

This PR adds full-screen image browsing to the dashboard file library, with filtering, zooming, keyboard and swipe navigation, downloads, date grouping, and cross-page traversal. The current implementation preserves an open gallery through background refreshes, resets pagination when grouping changes, and uses image-ID anchoring for navigation when the library ordering changes.

Confidence Score: 5/5

Safe to merge; there are no outstanding blocking issues.

The previously reported gallery refresh behavior is fully addressed: background file-list refreshes retain the active gallery session, while filter changes still close it. The grouping behavior is fully addressed because changing or disabling grouping resets the page to 1. The prior file-grid navigation concern was correctly conceded: FlintSH explained that ordinary thumbnail clicks are intentionally the gallery entry point, with file-page access retained through the filename, Manage → Open file, and modified thumbnail clicks. The prior refreshed-page navigation thread was resolved by Greptile without explanation; the current implementation uses the active image ID as the navigation anchor rather than relying on a stale numeric page.

_{Reviews (4): Last reviewed commit: "Anchor image navigation to the current f..." | Re-trigger Greptile}