Update admin theme/layout and refresh README details.

Align the project baseline with the latest admin interface styling and layout structure while documenting setup and usage updates in README.

apps/api/scripts/bootstrap_install.py

@@ -0,0 +1,28 @@
+from __future__ import annotations
+
+import sys
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[1]
+if str(ROOT) not in sys.path:
+    sys.path.insert(0, str(ROOT))
+
+from app.core.install_secrets import ensure_install_secrets
+
+
+def main() -> None:
+    status = ensure_install_secrets()
+    if status.created:
+        print(f"Created install secrets at {status.path}")
+        print(
+            "\nIf docker compose was already started without install.env, reset the Postgres volume "
+            "before the next start (local dev only — deletes DB data):\n"
+            "  docker compose --profile docker-web down -v\n"
+            "  docker compose --profile docker-web up -d --build"
+        )
+    else:
+        print(f"Install secrets already exist at {status.path}")
+
+
+if __name__ == "__main__":
+    main()