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

README.md

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+# Gitea Act Runner (DinD + cache)
+
+Stable Gitea Actions runner for building Rust projects. Runs jobs in an isolated
+Docker-in-Docker daemon with the built-in cache server enabled and multiple
+parallel jobs.
+
+## Setup on a new build machine
+
+Requires Docker + Docker Compose.
+
+```bash
+cp .env.example .env
+# edit .env: set GITEA_RUNNER_NAME (unique per machine) and a fresh
+# GITEA_RUNNER_REGISTRATION_TOKEN from Gitea -> Actions -> Runners -> Create Runner
+docker compose up -d
+```
+
+Verify:
+
+```bash
+docker compose ps                            # both containers up, dind healthy
+docker logs gitea-runner-wsl 2>&1 | tail     # "declare successfully"
+```
+
+## Config
+
+- **Parallel jobs**: `config.yaml` -> `runner.capacity` (default 4)
+- **Job images**: `config.yaml` -> `runner.labels` (ubuntu-latest/22.04/24.04)
+- **Cache**: enabled in `config.yaml`; layer cache persists in the `dind-storage` volume
+
+## Rust workflows
+
+Copy `example-rust-workflow.yaml` to your repo at `.gitea/workflows/build.yaml`.
+It uses `actions-rust-lang/setup-rust-toolchain` which caches `~/.cargo` and
+`target/` via the runner's cache server.
+
+## Manage
+
+```bash
+docker compose up -d      # apply config changes
+docker compose down       # stop (registration persists in volume)
+docker compose pull       # update runner/dind images
+```
+
+> Each machine needs a unique `GITEA_RUNNER_NAME` and its own registration token.
+> Run `docker compose down -v` to fully reset (drops registration + caches).