Bug

After creating a new album whose chosen image directory already contained a stale `photomap_index/embeddings.npz` from a prior session (e.g. recreating an album over the same folder), creating the album appeared to succeed but the indexing UI got stuck at "Index updated …" in orange at 0% completion that never advanced. The new album silently inherited the old index — searches and the UMAP were against the prior session's image set, not the current one.

Root cause

Two compounding bugs:

1. `startAutoIndexing` never actually started indexing. It's the only entry point that runs after `addAlbum`, and it just called `showProgressUI` on a 500 ms timer with a comment "Don't start indexing again - it's already running." The only path that does start indexing for a new album was the `albumIndexError` event fired from `getIndexMetadata` when the index returns 404. With a stale `embeddings.npz` already on disk, the metadata fetch succeeds, no error event fires, and `/update_index_async/` is never POSTed.

2. CSS `!important` orange wins over inline green. `updateAlbumCardIndexStatus` set `status.style.color = "green"` inline but never reset `className`. The CSS for `.index-status.indexing` carries `color: #ff9800 !important` (so the in-progress state wins over the inline updates that `updateProgressStatus` makes per status transition). When `showProgressUI` runs first and sets `className = "index-status indexing"`, the inline green that `updateAlbumCardIndexStatus` sets afterwards has no visual effect.

Fix

• `startAutoIndexing` now scrolls the album card's indexing section into view, then calls `startIndexing(albumKey, albumCard)` directly. `startIndexing` is already idempotent — its backend-progress probe attaches to an in-flight run instead of double-POSTing — so the no-prior-index path (where the `albumIndexError` listener also calls `startIndexing`) still triggers exactly one backend request.
• `updateAlbumCardIndexStatus` resets `className = "index-status"` before applying the inline color, so a stale state class can't override.

Test plan

• `npm run lint` + `npm run format:check` — clean
• `npm test` — 288 passed
• `pytest tests/backend` — 257 passed (no backend changes, ran for safety)
• Manual repro:
  1. Create an album pointing at a directory, let it index.
  2. Delete the album from PhotoMap (leave the `photomap_index/` directory on disk).
  3. Re-create an album with the same image directory.
  4. Before fix: orange "Index updated …" at 0% forever.
  5. After fix: indexing kicks off, progress UI advances scanning → indexing → mapping → green "Indexing completed successfully".

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