ci: compile-check examples/ to prevent example rot

Adds `python -m compileall examples` to the lint job so the SDK examples can't
silently break (ruff already lints them; this adds import/syntax validation).

Author: Patel230

.github/workflows/ci.yml

@@ -56,6 +56,8 @@ jobs:
         run: ruff check .
       - name: ruff format --check
         run: ruff format --check .
+      - name: examples compile (anti-rot)
+        run: python -m compileall examples
 
   typecheck:
     name: typecheck (mypy --strict)