feat: progressively cache optional PWA features (Closes #619)

src/frontend_bundle.py

@@ -114,11 +114,20 @@ def build_frontend(frontend_dir: Path) -> FrontendBuild:
     for source in sources:
         if source != WORKER_RUNTIME_SOURCE:
             worker = worker.replace(f"  BASE + '{source}',\n", "")
+    eager_feature = feature_bundles["today-timer"]
+    optional_features = {
+        name: bundle for name, bundle in feature_bundles.items() if name != "today-timer"
+    }
     worker = worker.replace(
         "  BASE + 'static/dashboard.css',\n",
         "  BASE + 'static/dashboard.css',\n"
         + f"  BASE + '{core.runtime_name}',\n"
-        + "".join(f"  BASE + '{bundle.runtime_name}',\n" for bundle in feature_bundles.values()),
+        + f"  BASE + '{eager_feature.runtime_name}',\n",
+    )
+    worker = worker.replace(
+        "const OPTIONAL_FEATURES = [\n",
+        "const OPTIONAL_FEATURES = [\n"
+        + "".join(f"  BASE + '{bundle.runtime_name}',\n" for bundle in optional_features.values()),
     )
     worker = CACHE_DECLARATION.sub(
         "const CACHE = 'stackchain-dashboard-shell-BUILD';", worker, count=1