ci: add quality gate workflow

Runs fmt-check, vet, and test on push to main and PRs.
Skips docs-only changes. Uses go-version-file for version pinning.

Author: vnykmshr

.github/workflows/ci.yml

@@ -0,0 +1,21 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+    paths-ignore: [docs/**]
+  pull_request:
+    branches: [main]
+    paths-ignore: [docs/**]
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+      - run: make fmt-check
+      - run: make vet
+      - run: make test