fix(web): seven web UI bugs, and remove dead plugins_manager.js helpers (#647)

- Operation History: the plugin filter lists the installed plugin ids
  instead of one option, "plugins" (Object.keys of {plugins: [...]}).
- Ctrl/Cmd+S submits the active tab's first visible form with
  requestSubmit() (validation and onsubmit guards run) instead of a bare
  Event on the first form in the document; skipped inside a modal dialog
  and on tabs without a form.
- Overview "Check Updates" confirms like "Update Code", takes its button
  explicitly (no implicit global event) and shows the server's message.
  Both, and the Tools tab git pull, raise the restart-pending banner on
  restart_required.
- Tools: toolsAction and diagnostics show the server's error message;
  only a non-JSON body falls back to HTTP <status>.
- Installed list after uninstall: PluginAPI writes clear the throttler's
  GET cache, a forced loadInstalledPlugins clears it too, and the
  post-uninstall reload goes through refreshInstalledPlugins().
- Plugin widgets load from /static/plugin-widgets/ only (the other two
  paths have no route).
- Raw JSON editor escapes the parse error; slider escapes value/min/max/step.
- Removed the unreferenced array-of-objects and key-value helpers from
  plugins_manager.js, the textarea auto-resize and Ctrl+R handlers in
  app.js, and a redundant ?v= on the plugins_manager.js script tag.

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

web_interface/templates/v3/partials/tools.html

@@ -451,9 +451,11 @@
         })
         .then(r => {
             if (!r.ok) {
+                // Only a non-JSON body falls back to the status code; the
+                // rejection carrying the server's message must not be caught.
                 return r.json()
-                    .then(d => Promise.reject(new Error(d.message || `HTTP ${r.status}`)))
-                    .catch(() => Promise.reject(new Error(`HTTP ${r.status}`)));
+                    .catch(() => null)
+                    .then(d => Promise.reject(new Error((d && d.message) || `HTTP ${r.status}`)));
             }
             return r.json();
         })
@@ -465,6 +467,14 @@
                 showOutput ? (data.output || '') : '',
                 showPluginDetails ? (data.details || []) : null
             );
+            // A pull replaces files on disk; the services keep running the
+            // code they loaded at boot until restarted.
+            if (ok && action === 'git_pull' && data.restart_required &&
+                    typeof window.showRestartPending === 'function') {
+                window.showRestartPending(
+                    'Update installed \u2014 restart the display and web ' +
+                    'services to run the new code');
+            }
         })
         .catch(err => {
             showResult(resultId, false, 'Request failed: ' + err.message);
@@ -717,8 +727,8 @@
         fetch('/api/v3/system/status')
             .then(r => {
                 if (!r.ok) return r.json()
-                    .then(d => Promise.reject(d.message || `HTTP ${r.status}`))
-                    .catch(() => Promise.reject(`HTTP ${r.status}`));
+                    .catch(() => null)
+                    .then(d => Promise.reject((d && d.message) || `HTTP ${r.status}`));
                 return r.json();
             })
             .then(res => {