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/HeapConvertDialog.svelte

@@ -24,7 +24,7 @@
 		type PpFolder
 	} from '$lib/services/photoprism';
 	import { filters, setSection } from '$lib/stores/filters.svelte';
-	import { isAuthenticated } from '$lib/stores/session.svelte';
+	import { isAuthenticated, toOriginalsPath } from '$lib/stores/session.svelte';
 	import FolderTree, { buildTree } from './FolderTree.svelte';
 
 	interface Props {
@@ -95,10 +95,13 @@
 		// pickedPath === '' is the root selection; falsy check would
 		// wrongly block it. Distinguish `null` (nothing picked) from `''`.
 		if (!heap || pickedPath === null) return;
+		// pickedPath is user-relative (listFolders strips BasePath). The
+		// sidecar moves files on disk so it needs a server-absolute path —
+		// translate before submitting.
 		convertMut.mutate({
 			uid: heap.UID,
 			body: {
-				targetFolder: pickedPath,
+				targetFolder: toOriginalsPath(pickedPath),
 				mode,
 				subfolder: subfolder.trim() || null,
 				deleteHeap: mode === 'move' && deleteHeap