feat: add user profile with avatar, bio, and lifetime stats

- Add profile fields to HikariConfig (name, avatar path, bio)
- Create ProfilePanel component with trans-pride themed styling
- Add profile button to StatusBar for easy access
- Display lifetime stats (messages, tokens, code blocks, files, cost)
- Show achievement completion progress bar
- Support file picker for avatar image selection
- Remove global stats from StatsDisplay (now in Profile)

Co-Authored-By: Hikari <hikari@nhcarrigan.com>

src/lib/components/ConfigSidebar.svelte

@@ -30,6 +30,9 @@
     streamer_mode: false,
     streamer_hide_paths: false,
     compact_mode: false,
+    profile_name: null,
+    profile_avatar_path: null,
+    profile_bio: null,
   });
 
   let isOpen = $state(false);