Session fixes: auth working, frontend files created, running locally

- Fixed circular imports in API files
- Created missing frontend lib files (api.ts, socket.ts, types.ts)
- Fixed register endpoint to return token instead of user
- Updated Anthropic client version
- Backend running locally on port 8000
- Frontend running on port 3000
- Authentication working
- Still need: channel response fix, WebSocket auth fix

docker/Dockerfile.backend

@@ -6,7 +6,7 @@ WORKDIR /app
 RUN apt-get update && apt-get install -y \
     libpango-1.0-0 \
     libpangoft2-1.0-0 \
-    libgdk-pixbuf2.0-0 \
+    libgdk-pixbuf-2.0-0 \
     libffi-dev \
     shared-mime-info \
     && rm -rf /var/lib/apt/lists/*