[fix](trx-frontend-http): fix map-core.js crash when cached scripts race app.js

Dynamic scripts (map-core.js etc.) are effectively async and can execute
before the defer'd app.js that creates window.trx. When map-core.js is
served from browser cache it loads instantly and crashes on
`const T = window.trx` (undefined), preventing window.trx.map from
ever being set — the map never initialises and Ctrl+R is needed.

Move eager plugin loading from the inline script to app.js, triggered
via window.loadEagerPlugins() after window.trx is fully populated.
This guarantees the namespace exists before any plugin script runs.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

src/trx-client/trx-frontend/trx-frontend-http/assets/web/app.js

@@ -4766,6 +4766,10 @@ Object.defineProperties(window.trx, {
   locationSubtitle:          { get() { return locationSubtitle; } },
 });
 
+// Load plugin scripts now that window.trx is populated.  Dynamic scripts are
+// async so they must not be created before the namespace they depend on exists.
+if (typeof window.loadEagerPlugins === "function") window.loadEagerPlugins();
+
 // Start the app
 initializeApp();
 window.addEventListener("resize", resizeHeaderSignalCanvas);