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/components/brainstorm/brainstorm-share-dialog.tsx

@@ -137,8 +137,8 @@ export function BrainstormShareDialog({
       <DialogContent className="sm:max-w-md bg-white dark:bg-[#1A1A1A] border-border rounded-2xl">
         <DialogHeader>
           <DialogTitle className="flex items-center gap-2 text-foreground">
-            <div className="w-7 h-7 rounded-lg bg-orange-500/10 flex items-center justify-center">
-              <UserPlus size={14} className="text-orange-500" />
+            <div className="w-7 h-7 rounded-lg bg-brand-accent/10 flex items-center justify-center">
+              <UserPlus size={14} className="text-brand-accent" />
             </div>
             <span className="font-serif">{t('brainstorm.shareDialogTitle')}</span>
           </DialogTitle>
@@ -159,7 +159,7 @@ export function BrainstormShareDialog({
               onFocus={() => results.length > 0 && setShowDropdown(true)}
               onBlur={() => setTimeout(() => setShowDropdown(false), 150)}
               placeholder={t('brainstorm.shareNameOrEmailPlaceholder')}
-              className="w-full px-4 py-3 text-sm border border-border rounded-xl bg-transparent focus:outline-none focus:ring-2 focus:ring-orange-500/20 focus:border-orange-500/40 transition-all"
+              className="w-full px-4 py-3 text-sm border border-border rounded-xl bg-transparent focus:outline-none focus:ring-2 focus:ring-brand-accent/20 focus:border-brand-accent/40 transition-all"
               autoFocus
             />
 
@@ -173,9 +173,9 @@ export function BrainstormShareDialog({
                       e.preventDefault()
                       selectUser(user)
                     }}
-                    className="w-full px-4 py-2.5 flex items-center gap-3 hover:bg-orange-500/5 transition-colors text-left"
+                    className="w-full px-4 py-2.5 flex items-center gap-3 hover:bg-brand-accent/5 transition-colors text-left"
                   >
-                    <div className="w-8 h-8 rounded-full bg-orange-500/10 flex items-center justify-center text-xs font-bold text-orange-600 shrink-0">
+                    <div className="w-8 h-8 rounded-full bg-brand-accent/10 flex items-center justify-center text-xs font-bold text-brand-accent shrink-0">
                       {(user.name || user.email).charAt(0).toUpperCase()}
                     </div>
                     <div className="min-w-0 flex-1">
@@ -214,7 +214,7 @@ export function BrainstormShareDialog({
           <button
             type="submit"
             disabled={!query.trim() || isPending}
-            className="w-full py-3 bg-orange-500 hover:bg-orange-600 text-white text-[10px] font-bold uppercase tracking-[0.15em] rounded-xl disabled:opacity-50 transition-all flex items-center justify-center gap-1.5"
+            className="w-full py-3 bg-brand-accent hover:bg-brand-accent/90 text-white text-[10px] font-bold uppercase tracking-[0.15em] rounded-xl disabled:opacity-50 transition-all flex items-center justify-center gap-1.5"
           >
             <UserPlus size={12} />
             {isPending ? t('brainstorm.shareSubmitting') : t('brainstorm.shareSubmit')}