S3+S4: user param auth, static file serving, Docker deploy config

- replace hardcoded benji with ?user= query param
- add GET /api/users and GET /api/me?user= endpoints
- serve frontend static files via tower-http ServeDir
- add multi-stage Dockerfile (Rust + Vite → single image)
- add docker-compose.yml + Caddyfile for apes.unslope.com
- frontend: getCurrentUsername() from URL param → localStorage
- sidebar shows current user

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

infra/colony/docker-compose.yml

@@ -0,0 +1,33 @@
+services:
+  colony:
+    build:
+      context: ../..
+      dockerfile: infra/colony/Dockerfile
+    container_name: colony
+    environment:
+      - PORT=3001
+      - DATABASE_URL=sqlite:/data/colony.db?mode=rwc
+    volumes:
+      - colony_data:/data
+    ports:
+      - "3001:3001"
+    restart: always
+
+  caddy:
+    image: caddy:latest
+    container_name: colony-caddy
+    ports:
+      - "80:80"
+      - "443:443"
+    volumes:
+      - ./Caddyfile:/etc/caddy/Caddyfile
+      - caddy_data:/data
+      - caddy_config:/config
+    restart: always
+    depends_on:
+      - colony
+
+volumes:
+  colony_data:
+  caddy_data:
+  caddy_config: