fix(web-ui): fix quick actions not firing, add toast feedback, suppress install handler warning

- base.html: add htmx:afterSettle listener to set data-loaded on tab
  containers after HTMX swaps their content, preventing the overview
  partial from being re-fetched (and handlers lost) on every tab switch
- base.html: call htmx.process() in loadOverviewDirect/loadPluginsDirect
  fallbacks so buttons get HTMX handlers even if HTMX finished its
  initial body scan before the fallback fetch completed
- overview.html + index.html (11 buttons): replace event.detail.xhr.responseJSON
  (undefined in HTMX 1.9.x) with JSON.parse(event.detail.xhr.responseText)
  so quick action toast notifications actually fire
- plugins_manager.js: add guarded htmx:afterSettle listener that only calls
  attachInstallButtonHandler when #install-plugin-from-url is in the DOM,
  eliminating the spurious console warning on non-plugin tab loads

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web_interface/static/v3/plugins_manager.js

@@ -7484,6 +7484,16 @@ setTimeout(function() {
     }, 500);
 }, 200);
 
+// Re-run install button wiring after HTMX settles the plugins tab content.
+// Guard with element check so it only fires when the plugins partial is in the DOM,
+// preventing spurious warnings on other tab loads.
+document.addEventListener('htmx:afterSettle', function() {
+    if (document.getElementById('install-plugin-from-url') &&
+        typeof window.attachInstallButtonHandler === 'function') {
+        window.attachInstallButtonHandler();
+    }
+});
+
 // ─── Starlark Apps Integration ──────────────────────────────────────────────
 
 (function() {