Add docker build, rewrite Actions for Gitea, and add healthcheck endpoint.

Dockerfile

@@ -0,0 +1,37 @@
+# ── Build stage ──────────────────────────────────────────────────────────────
+FROM rust:1-slim AS builder
+
+WORKDIR /build
+
+# Cache dependency compilation separately from application code.
+COPY Cargo.toml Cargo.lock build.rs ./
+# Dummy source so `cargo build` can compile dependencies without the real code.
+RUN mkdir src && echo 'fn main(){}' > src/main.rs \
+    && cargo build --release \
+    && rm src/main.rs
+
+# Build the real application.
+COPY src ./src
+COPY migrations ./migrations
+# Touch main.rs so Cargo detects the change and recompiles.
+RUN touch src/main.rs \
+    && cargo build --release
+
+# ── Runtime stage ─────────────────────────────────────────────────────────────
+FROM debian:bookworm-slim
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+        ca-certificates \
+        curl \
+    && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+COPY --from=builder /build/target/release/mikebase ./mikebase
+COPY migrations ./migrations
+
+EXPOSE 3000
+
+HEALTHCHECK --interval=30s --timeout=5s --start-period=5s --retries=3 \
+    CMD curl -f http://localhost:3000/health || exit 1
+
+ENTRYPOINT ["./mikebase"]