feat: comprehensive project improvements

- Fix 14 Clippy warnings across server and bot-sdk
- Add 67 unit tests (32 bot-sdk, 34 server, 1 doctest)
- Add Prometheus metrics endpoint (/api/metrics)
- Add structured JSON logging (EIFELDC_LOG_FORMAT=json)
- Add release workflow (Docker push + GitHub Release + Tauri builds)
- Add rate limiting middleware (EIFELDC_RATE_LIMIT)
- Add CORS restriction (EIFELDC_CORS_ORIGINS)
- Add session token expiry (EIFELDC_SESSION_TTL)
- Add input validation (username/password/homeserver length limits)
- Add upload size limit (EIFELDC_MAX_UPLOAD_MB)
- Upgrade Tauri client from v1 to v2
- Add session store with SQLite persistence
- Add proper error types and cleanup across all crates
- Format all code with cargo fmt
- Update CI pipeline with fmt, clippy, test, frontend, and Tauri checks
- Add README with full API reference and setup guide

Dockerfile

@@ -12,15 +12,27 @@ WORKDIR /app
 
 COPY Cargo.toml Cargo.lock ./
 COPY server/Cargo.toml server/Cargo.toml
-RUN mkdir -p server/src && echo "fn main() {}" > server/src/main.rs
-RUN cargo build --release -p eifeldc-server && rm -rf server/src
+COPY bot-sdk/Cargo.toml bot-sdk/Cargo.toml
+COPY client/Cargo.toml client/Cargo.toml
+
+RUN mkdir -p server/src bot-sdk/src client/src && \
+    echo "fn main() {}" > server/src/main.rs && \
+    echo "" > bot-sdk/src/lib.rs && \
+    echo "" > client/src/main.rs
+
+RUN cargo build --release -p eifeldc-server || true
+RUN rm -rf server/src bot-sdk/src client/src
 
 COPY server/src server/src
-RUN touch server/src/main.rs && cargo build --release -p eifeldc-server
+COPY bot-sdk/src bot-sdk/src
+COPY client/src client/src
+
+RUN touch server/src/main.rs bot-sdk/src/lib.rs client/src/main.rs && \
+    cargo build --release -p eifeldc-server
 
 FROM debian:bookworm-slim
 
-RUN apt-get update && apt-get install -y ca-certificates libssl3 && rm -rf /var/lib/apt/lists/*
+RUN apt-get update && apt-get install -y ca-certificates libssl3 curl && rm -rf /var/lib/apt/lists/*
 
 RUN useradd -m -d /home/eifeldc eifeldc
 
@@ -31,7 +43,13 @@ USER eifeldc
 
 ENV EIFELDC_STATIC_DIR=/usr/share/eifeldc/client
 ENV RUST_LOG=eifeldc_server=info,tower_http=info
+ENV LIVEKIT_API_KEY=devkey
+ENV LIVEKIT_API_SECRET=devsecret
+ENV LIVEKIT_URL=ws://livekit:7880
 
 EXPOSE 3000
 
+HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
+    CMD curl -f http://localhost:3000/api/current-user || exit 1
+
 CMD ["eifeldc-server"]