fix: Alpine compatibility + READMEs + roadmap

- setup-node: detect Alpine/Debian, use apk or NodeSource
- setup-aws: use pip on Alpine (musl), binary on Debian (glibc)
- setup-go: fix version parsing for Alpine (no grep -P)
- README per action with usage examples and input docs
- PLAN.md: roadmap for runner images, labels, Lambda dispatch

checkout/README.md

@@ -0,0 +1,33 @@
+# tinqs/ci/checkout
+
+Clones a repository from tinqs.com (self-hosted Gitea) using plain `git clone`.
+
+Works on any runner with git installed — Alpine, Debian, or pre-baked images. No Node.js runtime, no GitHub API dependency.
+
+## Usage
+
+```yaml
+- uses: tinqs/ci/checkout@v1
+```
+
+### With options
+
+```yaml
+- uses: tinqs/ci/checkout@v1
+  with:
+    repository: 'tinqs/engine'    # default: current repo
+    ref: 'tinqs/main'             # default: current branch
+    depth: '0'                    # default: 1 (shallow)
+    token: ${{ secrets.TOKEN }}   # default: none (public clone)
+    path: 'engine'                # default: . (current dir)
+```
+
+## Inputs
+
+| Input | Default | Description |
+|-------|---------|-------------|
+| `repository` | `${{ github.repository }}` | Repository in `owner/repo` format |
+| `ref` | `${{ github.ref_name }}` | Branch or tag |
+| `depth` | `1` | Clone depth (0 = full history) |
+| `path` | `.` | Directory to clone into |
+| `token` | `` | Gitea access token for private repos |