feat(web): sidebar root folder + folder counts, drill-in colors/tags/ratings, click semantics rework

Sidebar
- New `/` root-folder entry at the top of the Folders group. Active
  when the timeline is scoped to root; the photo grid post-filters to
  `Path === ''` because PhotoPrism's `path:` operator can't express an
  exact-root match. Collapsible chevron, persisted to its own
  localStorage key, and a kebab carrying just "New subfolder".
- Per-folder count badges. `/api/v1/photos?q=path:X&count=1000` per
  folder in parallel via `listFolderCounts`; root count derived from
  `config.count.all − Σ subfolder counts`.
- Folder tree starts at depth=1 under the root so nested rows indent
  visually relative to `/`.
- Footer matches the Toolbar / action-bar h-9 height.

Timeline interaction
- Single click on a tile selects only that tile (clears others); the
  preview now lives on dblclick. Modifier clicks still go through
  `gridKeyNav`'s document handler (shift = range, cmd/ctrl = toggle).
- `x` (archive) now actually archives — PhotoPrism's photo PUT
  silently drops the Archived field, so we route through
  /batch/photos/{archive,restore} the same way the BulkActionBar
  already did. Mirror for `u`.
- Preview close restores the timeline focus + scrolls the last-shown
  photo into view via `forcedExpand`+`scrollTileIntoView` so it
  actually mounts (selection ring would otherwise stay invisible when
  the user navigated far in preview).
- `applyFolderScope` only narrows the timeline to root when the active
  view is a folder view (no heap / search / non-default section), so
  label clicks / heap views / favorites no longer drop subfolder
  photos.

Action bar
- Inline `h-9` row at the bottom of the main column (not `fixed`),
  matching the Toolbar's visual language. Right sidebar stays full
  height — the bar only spans the timeline width.
- Approve action wired for the review pile.

Colors / Tags / Ratings drill-ins
- New shared `PhotoGrid` component owning tile rendering, selection
  styling, single-click-selects + dblclick-previews, and `setOrder`
  for arrow-key nav.
- Each route's drill-in `<main>` carries `use:gridKeyNav` and a
  trailing `<BulkActionBar />` so shift/cmd/ctrl click, arrow keys,
  and the keyboard shortcuts work the same as the timeline.
- Tags switches from `goto('/?q=label:…')` to an in-place drill-in
  with a back button, mirroring `/colors`'s flow.
- Category cards + drill-in photo cards honour the global
  `view.thumbnailSize` (XS–XL) so the timeline's size selector now
  reaches into all four grids.

Settings
- General-settings dialog merges Appearance into UI and switches free
  text inputs to selects for the PhotoPrism theme / language / start
  page / map style (the value-from-server prepends if it's outside
  the curated list so we never silently rewrite a custom value). Time
  zone uses `<datalist>` with `Intl.supportedValuesOf('timeZone')`.

Sidecar
- Heap convert runs reindex synchronously per source path so the
  client's invalidate-and-refetch sees the moved files.

Inbox
- New /inbox route stub for the upcoming import workflow.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

web/src/lib/actions/nearBottom.ts

@@ -27,19 +27,24 @@ export interface NearBottomParams {
 export function nearBottom(node: HTMLElement, params: NearBottomParams) {
 	let current: NearBottomParams = params;
 	let io: IntersectionObserver | null = null;
+	// IntersectionObserver only emits on state changes. With a 4-viewport
+	// preload zone, the sentinel typically stays continuously intersecting
+	// across a whole fetchNextPage cycle: enabled flips false (fetching),
+	// the IO callback runs but no-ops, enabled flips back true — and no new
+	// event is emitted because the intersection state never changed. We'd
+	// stall mid-pagination. Remember the last reported intersection so the
+	// next `enabled` rising edge can re-fire manually.
+	let lastIntersecting = false;
 
 	function buildObserver(p: NearBottomParams) {
 		io?.disconnect();
 		const preload = p.preloadPx ?? Math.max(800, window.innerHeight * 4);
 		io = new IntersectionObserver(
 			(entries) => {
-				if (!current.enabled) return;
 				for (const e of entries) {
-					if (e.isIntersecting) {
-						current.onHit();
-						return;
-					}
+					lastIntersecting = e.isIntersecting;
 				}
+				if (lastIntersecting && current.enabled) current.onHit();
 			},
 			{
 				root: p.root ?? null,
@@ -57,11 +62,15 @@ export function nearBottom(node: HTMLElement, params: NearBottomParams) {
 		update(next: NearBottomParams) {
 			const rootChanged = next.root !== current.root;
 			const preloadChanged = next.preloadPx !== current.preloadPx;
+			const enabledRose = !current.enabled && !!next.enabled;
 			current = next;
-			// `enabled` and `onHit` are read live inside the callback,
-			// so they don't require rebuilding the observer. Root and
-			// preloadPx are baked in at construction.
-			if (rootChanged || preloadChanged) buildObserver(current);
+			if (rootChanged || preloadChanged) {
+				buildObserver(current);
+				return;
+			}
+			// `enabled` rising while the sentinel is still in the preload
+			// zone — no IO event coming, so fire manually.
+			if (enabledRose && lastIntersecting) current.onHit();
 		},
 		destroy() {
 			io?.disconnect();