fix: brainstorm infinite loop, ghost cursor, embedding ::vector cast, semantic search, billing stats, usage meter accordion

- Fix useBrainstormSocket: stable guestId via useRef, remove setState in cleanup
- Fix GhostCursor: direct DOM manipulation via refs, no useState re-renders
- Fix all SQL embedding queries: add ::vector cast on text columns
- Fix embedding truncation to 15000 chars (under 8192 token limit)
- Fix NoteEmbedding INSERT: remove non-existent updatedAt column
- Fix billing page: show all quota stats in grid instead of single metric
- Fix usage meter: accordion expand/collapse, per-feature detail
- Fix semantic search: rebuild 103 note embeddings, ::vector cast on vectorSearch
- Fix brainstorm expand/manual-idea/create: ::vector cast on embedding SQL

memento-note/app/api/notebooks/[id]/route.ts

@@ -98,7 +98,7 @@ export async function PATCH(
       })
     }
 
-    try { revalidatePath('/') } catch {}
+    try { revalidatePath('/home') } catch {}
 
     return NextResponse.json({ success: true })
   } catch (error) {
@@ -143,7 +143,7 @@ export async function DELETE(
 
     await prisma.notebook.delete({ where: { id } })
 
-    try { revalidatePath('/') } catch {}
+    try { revalidatePath('/home') } catch {}
 
     return NextResponse.json({
       success: true,

memento-note/app/api/notebooks/reorder/route.ts

@@ -47,7 +47,7 @@ export async function POST(request: NextRequest) {
 
     await prisma.$transaction(updates)
 
-    revalidatePath('/')
+    revalidatePath('/home')
 
     return NextResponse.json({
       success: true,

memento-note/app/api/notebooks/route.ts

@@ -105,7 +105,7 @@ export async function POST(request: NextRequest) {
       }
     })
 
-    try { revalidatePath('/') } catch {}
+    try { revalidatePath('/home') } catch {}
 
     return NextResponse.json({
       success: true,