chore(observability): add CSS mirror sync helper

scripts/sync_observability_css.py

@@ -0,0 +1,49 @@
+#!/usr/bin/env python3
+"""Sync the canonical observability CSS to the Flask-served static path.
+
+The project keeps the design-system source at:
+  static/css/observability-system.css
+
+Production Flask static serving currently exposes:
+  web/static/css/observability-system.css
+
+This helper keeps the two files byte-identical so deploys do not regress into
+"HTML links the CSS but /static/css/observability-system.css is 404/stale".
+"""
+
+from __future__ import annotations
+
+import shutil
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[1]
+SOURCE = ROOT / "static/css/observability-system.css"
+TARGET = ROOT / "web/static/css/observability-system.css"
+
+
+def main() -> int:
+    if not SOURCE.exists():
+        print(f"ERROR: missing source CSS: {SOURCE.relative_to(ROOT)}")
+        return 1
+
+    TARGET.parent.mkdir(parents=True, exist_ok=True)
+    source_bytes = SOURCE.read_bytes()
+    target_bytes = TARGET.read_bytes() if TARGET.exists() else b""
+
+    if source_bytes == target_bytes:
+        print("Observability CSS sync: already in sync")
+        print(f"- source: {SOURCE.relative_to(ROOT)}")
+        print(f"- target: {TARGET.relative_to(ROOT)}")
+        return 0
+
+    shutil.copyfile(SOURCE, TARGET)
+    print("Observability CSS sync: synced")
+    print(f"- source: {SOURCE.relative_to(ROOT)}")
+    print(f"- target: {TARGET.relative_to(ROOT)}")
+    print(f"- bytes: {len(source_bytes)}")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())