Add basic lint, build, and test CI workflow

Adds .github/workflows/ci.yml with independent lint and ci jobs running
on pull requests and pushes to the default branch. No publish or deploy
steps.

Author: trly

.github/workflows/ci.yml

@@ -0,0 +1,42 @@
+name: CI
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+
+permissions:
+  contents: read
+
+jobs:
+  lint:
+    name: lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+      - uses: actions/setup-python@v6
+        with:
+          python-version: '3.11'
+      - name: Lint (syntax check)
+        run: |
+          echo "No dedicated linter configured; running Python syntax check via compileall."
+          python -m compileall libs stack
+  ci:
+    name: ci
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+      - uses: actions/setup-python@v6
+        with:
+          python-version: '3.11'
+      - name: Install Poetry
+        run: pip install poetry
+      - name: Build and test
+        run: |
+          PROJECTS="libs/libml libs/libmq libs/libtelemetry stack/service-ml-common stack/service-ml-custom stack/service-one stack/service-two"
+          for proj in $PROJECTS; do
+            echo "==== Building $proj ===="
+            ( cd "$proj" && poetry build )
+          done
+          echo "No test files found in the repository; build completed."