Gitea Act Runner: DinD stack with cache + parallel jobs

Stable docker-compose setup for building Rust projects on Gitea Actions.
DinD-isolated daemon, built-in cache server, capacity=4 parallel jobs,
healthcheck-gated startup. Portable to other build machines via .env.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HU4wDwdydNZpR3YkMiYYy8

example-rust-workflow.yaml

@@ -0,0 +1,20 @@
+# Copy to your repo at: .gitea/workflows/build.yaml
+name: Build Rust
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust toolchain
+        uses: actions-rust-lang/setup-rust-toolchain@v1
+        # This action already wires Swatinem/rust-cache under the hood,
+        # caching ~/.cargo registry + target/ via the runner's cache server.
+
+      - name: Build
+        run: cargo build --release --locked
+
+      - name: Test
+        run: cargo test --release --locked