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/lib/ai/services/semantic-search.service.ts

@@ -235,15 +235,15 @@ export class SemanticSearchService {
 
     const rows: Array<{ noteId: string; similarity: number }> = await prisma.$queryRawUnsafe(
       `SELECT n.id AS "noteId",
-              1 - (e."embedding" <=> ${vecParam}) AS similarity
+              1 - (e."embedding"::vector <=> ${vecParam}) AS similarity
        FROM "Note" n
        INNER JOIN "NoteEmbedding" e ON e."noteId" = n.id
        WHERE n."trashedAt" IS NULL
          AND n."isArchived" = false
          ${userClause}
          ${notebookClause}
-         AND 1 - (e."embedding" <=> ${vecParam}) >= ${thresholdParam}
-       ORDER BY e."embedding" <=> ${vecParam} ASC
+         AND 1 - (e."embedding"::vector <=> ${vecParam}) >= ${thresholdParam}
+       ORDER BY e."embedding"::vector <=> ${vecParam} ASC
        LIMIT ${limitParam}`,
       ...params
     )
@@ -356,10 +356,10 @@ export class SemanticSearchService {
       const vecStr = embeddingService.toVectorString(embedding)
 
       await prisma.$queryRawUnsafe(
-        `INSERT INTO "NoteEmbedding" ("id", "noteId", "embedding", "createdAt", "updatedAt")
-         VALUES (gen_random_uuid(), $1, $2::vector, now(), now())
+        `INSERT INTO "NoteEmbedding" ("id", "noteId", "embedding", "createdAt")
+         VALUES (gen_random_uuid(), $1, $2::vector, now())
          ON CONFLICT ("noteId")
-         DO UPDATE SET "embedding" = $2::vector, "updatedAt" = now()`,
+         DO UPDATE SET "embedding" = $2::vector`,
         noteId,
         vecStr
       )
@@ -427,7 +427,7 @@ export class SemanticSearchService {
         AND n."trashedAt" IS NULL
         AND n."userId" = $3
         ${noteFilter}
-      ORDER BY dc."embedding" <=> $1::vector
+      ORDER BY dc."embedding"::vector <=> $1::vector
       LIMIT $2`,
       ...params
     ) as any[]