Initial commit: EifelDC - Discord-like Matrix chat platform

Includes server (Rust/Axum API proxy with voice management),
Tauri desktop client with Svelte UI, bot-sdk, Docker infra
(Synapse, PostgreSQL, Coturn, Nginx), and CI/CD pipeline.

server/Dockerfile

@@ -0,0 +1,27 @@
+FROM rust:1.82-bookworm AS builder
+
+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 server/src server/src
+RUN touch server/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 useradd -m -d /home/eifeldc eifeldc
+USER eifeldc
+
+COPY --from=builder /app/target/release/eifeldc-server /usr/local/bin/eifeldc-server
+
+ENV EIFELDC_STATIC_DIR=/usr/share/eifeldc/client
+ENV RUST_LOG=eifeldc_server=info,tower_http=info
+
+EXPOSE 3000
+
+CMD ["eifeldc-server"]