Add ads system, diversify callers, update website descriptions

- Add ads playback system with backend endpoints and frontend UI
- Diversify AI callers: randomize voices per session, expand jobs/problems/interests/quirks/locations
- Update website tagline and descriptions to "biologically questionable organisms"

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

backend/config.py

@@ -38,6 +38,7 @@ class Settings(BaseSettings):
     base_dir: Path = Path(__file__).parent.parent
     sounds_dir: Path = base_dir / "sounds"
     music_dir: Path = base_dir / "music"
+    ads_dir: Path = base_dir / "ads"
     sessions_dir: Path = base_dir / "sessions"
 
     class Config: