feat(web): scope library views to per-user BasePath

PhotoPrism's user entity carries a per-user BasePath; the web app now
mirrors that scope client-side so each user sees only their own subtree
in the sidebar, timeline, folder counts, and heap-convert target picker.
Admin without a BasePath is unchanged. Also removes the redundant
"✕ <folder>" pill below the folder tree.

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

web/src/lib/components/layout/SettingsDialog.svelte

@@ -23,6 +23,7 @@
 		type PpLogEntry,
 		type PpSettings
 	} from '$lib/services/photoprism';
+	import { userBasePath } from '$lib/stores/session.svelte';
 
 	interface Props {
 		open: boolean;
@@ -71,7 +72,16 @@
 	}
 
 	// ── Index tab ─────────────────────────────────────────────────────────
-	let indexForm = $state<IndexBody>({ path: '/', rescan: false, cleanup: false });
+	// Default the reindex path to the user's BasePath when scoping is on,
+	// so non-admins (and admins-with-BasePath) only rescan their own
+	// subtree. PhotoPrism's /index expects originals-relative paths with
+	// a leading slash; `'/'` means the whole library.
+	const _bp = userBasePath();
+	let indexForm = $state<IndexBody>({
+		path: _bp === '' ? '/' : `/${_bp}`,
+		rescan: false,
+		cleanup: false
+	});
 	const startIndexMut = createMutation(() => ({
 		mutationFn: (b: IndexBody) => startIndex(b),
 		onSuccess: (r) => toast.success(r.message || 'Indexing complete'),