frontend: working profile settings with sticky save + real account deletion

- ToggleRow supports controlled checked/onCheckedChange; CopyField copy works
- ProfilePanel loads/saves preferences via /api/settings, name via updateUser
- dirty tracking with a sticky save bar that follows the scroll
- Delete account: password-confirmed dialog wired to authClient.deleteUser
- clinician ID / handle now show the real session user

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/lib/settings.ts

@@ -0,0 +1,24 @@
+import { apiFetch } from "@/lib/api-client";
+
+// Per-user preferences persisted by the backend (`user_settings` table) as a
+// flat key → boolean/string map. Unknown keys are preserved, so features can
+// add settings without coordinating with this file.
+export type UserPreferences = Record<string, boolean | string>;
+
+export async function getSettings(): Promise<UserPreferences> {
+  const res = await apiFetch<{ preferences: UserPreferences }>("/api/settings");
+  return res.preferences ?? {};
+}
+
+export async function saveSettings(
+  preferences: UserPreferences,
+): Promise<UserPreferences> {
+  const res = await apiFetch<{ preferences: UserPreferences }>(
+    "/api/settings",
+    {
+      method: "PUT",
+      body: JSON.stringify({ preferences }),
+    },
+  );
+  return res.preferences ?? {};
+}