feat(profile)!: replace sidebar and add avatar navigation

Rename the global Sidebar route, UI, assets, analytics, and payment return context to Profile. Add accessible message-avatar navigation and preserve the source character across auth and logout flows.

BREAKING CHANGE: /sidebar has been removed; use /profile instead.

src/app/chat/components/message-bubble.tsx

@@ -32,6 +32,8 @@ export interface MessageBubbleProps {
   onUnlockVoiceMessage?: ChatMessageAction;
   onUnlockImageMessage?: ChatMessageAction;
   onOpenImage?: (displayMessageId: string) => void;
+  onUserAvatarClick?: () => void;
+  onCharacterAvatarClick?: () => void;
 }
 
 type ChatMessageAction = (
@@ -57,6 +59,8 @@ export function MessageBubble({
   onUnlockVoiceMessage,
   onUnlockImageMessage,
   onOpenImage,
+  onUserAvatarClick,
+  onCharacterAvatarClick,
 }: MessageBubbleProps) {
   const avatarUrl = useUserSelector((state) => state.context.avatarUrl);
 
@@ -67,7 +71,10 @@ export function MessageBubble({
         data-chat-message-id={displayMessageId}
         aria-label="AI message"
       >
-        <MessageAvatar isFromAI={true} />
+        <MessageAvatar
+          isFromAI={true}
+          onClick={onCharacterAvatarClick}
+        />
         <div className={styles.bubbleInlineSpacer} aria-hidden="true" />
         <MessageContent
           characterId={characterId}
@@ -120,7 +127,11 @@ export function MessageBubble({
         onOpenImage={onOpenImage}
       />
       <div className={styles.bubbleInlineSpacer} aria-hidden="true" />
-      <MessageAvatar isFromAI={false} userAvatarUrl={avatarUrl} />
+      <MessageAvatar
+        isFromAI={false}
+        userAvatarUrl={avatarUrl}
+        onClick={onUserAvatarClick}
+      />
     </div>
   );
 }