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

setup-go/README.md

@@ -0,0 +1,25 @@
+# tinqs/ci/setup-go
+
+Installs Go from go.dev and adds it to PATH.
+
+Downloads the official tarball — works on any Linux (Alpine, Debian, etc.). Skips installation if the correct version is already present in the runner image.
+
+## Usage
+
+```yaml
+- uses: tinqs/ci/setup-go@v1
+```
+
+### Specific version
+
+```yaml
+- uses: tinqs/ci/setup-go@v1
+  with:
+    go-version: '1.26.2'
+```
+
+## Inputs
+
+| Input | Default | Description |
+|-------|---------|-------------|
+| `go-version` | `1.26.2` | Go version to install |