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/Dockerfile

@@ -0,0 +1,29 @@
+# Stage 1: Build frontend
+FROM node:22-slim AS frontend
+WORKDIR /app/ui/colony
+COPY ui/colony/package.json ui/colony/package-lock.json ./
+RUN npm ci
+COPY ui/colony/ .
+RUN npm run build
+
+# Stage 2: Build backend
+FROM rust:1.86-slim AS backend
+RUN apt-get update && apt-get install -y pkg-config libssl-dev && rm -rf /var/lib/apt/lists/*
+WORKDIR /app
+COPY Cargo.toml Cargo.lock ./
+COPY crates/ crates/
+RUN cargo build --release -p colony
+
+# Stage 3: Runtime
+FROM debian:bookworm-slim
+RUN apt-get update && apt-get install -y ca-certificates && rm -rf /var/lib/apt/lists/*
+WORKDIR /app
+
+COPY --from=backend /app/target/release/colony /app/colony
+COPY --from=frontend /app/ui/colony/dist /app/static
+
+ENV PORT=3001
+ENV DATABASE_URL=sqlite:/data/colony.db?mode=rwc
+EXPOSE 3001
+
+CMD ["/app/colony"]