feat: per-user assistant name and system prompt customization

Each user can rename the AI assistant and edit their own system prompt in Settings.

src/modules/agent/components/assistant-bubble.tsx

@@ -7,9 +7,10 @@ import { AssistantPanel } from "./assistant-panel";
 type Props = {
   configured: boolean;
   userId: string;
+  assistantName: string;
 };
 
-export function AssistantBubble({ configured, userId }: Props) {
+export function AssistantBubble({ configured, userId, assistantName }: Props) {
   const [open, setOpen] = useState(false);
 
   return (
@@ -18,31 +19,36 @@ export function AssistantBubble({ configured, userId }: Props) {
         <div
           className="assistant-bubble-panel"
           role="dialog"
-          aria-label="Assistant"
+          aria-label={assistantName}
           aria-modal="false"
         >
           <div className="assistant-bubble-header">
             <div>
-              <div className="serif text-[15px] font-medium tracking-tight">Assistant</div>
+              <div className="serif text-[15px] font-medium tracking-tight">{assistantName}</div>
               <div className="muted text-[11px]">Household helper</div>
             </div>
             <button
               type="button"
               className="assistant-bubble-close"
-              aria-label="Close assistant"
+              aria-label={`Close ${assistantName}`}
               onClick={() => setOpen(false)}
             >
               <X className="size-4" />
             </button>
           </div>
-          <AssistantPanel key={userId} configured={configured} userId={userId} />
+          <AssistantPanel
+            key={userId}
+            configured={configured}
+            userId={userId}
+            assistantName={assistantName}
+          />
         </div>
       ) : null}
 
       <button
         type="button"
         className="assistant-bubble-trigger"
-        aria-label={open ? "Close assistant" : "Open assistant"}
+        aria-label={open ? `Close ${assistantName}` : `Open ${assistantName}`}
         aria-expanded={open}
         onClick={() => setOpen((current) => !current)}
       >