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/agents/agent-detail-view.tsx

@@ -353,7 +353,7 @@ export function AgentDetailView({
           <div className="flex items-end justify-between">
             <div className="space-y-4">
               <div className="flex items-center gap-3">
-                <div className="p-4 bg-foreground text-background rounded-2xl shadow-xl shadow-foreground/10">
+                <div className="p-4 bg-brand-accent text-white rounded-2xl shadow-xl shadow-brand-accent/10">
                   <Icon className="w-8 h-8" />
                 </div>
                 <div className="space-y-1">
@@ -369,7 +369,7 @@ export function AgentDetailView({
                       {isNew ? t('agents.newBadge') : `ID: ${agent?.id?.slice(0, 8)}`}
                     </span>
                     {!isNew && agent?.isEnabled && (
-                      <span className="text-[10px] font-bold uppercase tracking-widest px-2 py-1 bg-primary/10 text-primary rounded-md">
+                      <span className="text-[10px] font-bold uppercase tracking-widest px-2 py-1 bg-brand-accent/10 text-brand-accent rounded-md">
                         {t('agents.actions.toggleOn')}
                       </span>
                     )}
@@ -386,7 +386,7 @@ export function AgentDetailView({
                 {successRate !== null && (
                   <div className="flex flex-col items-end gap-1">
                     <span className="opacity-40">Succès</span>
-                    <span className="text-primary">{successRate}%</span>
+                    <span className="text-brand-accent">{successRate}%</span>
                   </div>
                 )}
               </div>
@@ -751,7 +751,7 @@ export function AgentDetailView({
             <div className="space-y-10">
               <section className="space-y-6">
                 <h3 className={sectionTitleCls}>{t('agents.form.frequency')}<FieldHelp tooltip={t('agents.help.tooltips.frequency')} /></h3>
-                <div className="bg-foreground rounded-3xl p-8 space-y-8 text-background shadow-2xl shadow-foreground/20 relative overflow-hidden">
+                <div className="bg-ink rounded-3xl p-8 space-y-8 text-paper shadow-2xl shadow-ink/20 relative overflow-hidden">
                   <div className="absolute top-0 right-0 p-4 opacity-10">
                     <Clock className="w-24 h-24" />
                   </div>