fix(account-settings): clear stale pw error on input + live header avatar update

- Password form errors (wrong pw, mismatch) now clear on first keystroke
  in any password field instead of persisting until next submit.
- Avatar upload now bumps avatarVersion in auth store and sets hasAvatar=true,
  so the header avatar switches to the uploaded image immediately without reload.
- Header img src uses ?v={avatarVersion} as cache-buster to force browser to
  fetch the new avatar when version increments.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/web/src/lib/stores/auth-store.ts

@@ -11,8 +11,10 @@ export interface AuthUser {
 
 interface AuthState {
   user: AuthUser | null;
+  avatarVersion: number;
   setUser: (user: AuthUser) => void;
   clearUser: () => void;
+  bumpAvatarVersion: () => void;
 }
 
 /**
@@ -22,6 +24,8 @@ interface AuthState {
  */
 export const useAuthStore = create<AuthState>()((set) => ({
   user: null,
+  avatarVersion: 0,
   setUser: (user) => set({ user }),
   clearUser: () => set({ user: null }),
+  bumpAvatarVersion: () => set((s) => ({ avatarVersion: s.avatarVersion + 1 })),
 }));