feat(plugins): plugin pages, per-user config, capabilities gate, mobile/telegram refactors

- Plugin HTTP routes + web pages (plugin-page-host, plugin-catalog, plugin-detail)
- Plugin access grants + per-user config (DB tables + API + frontend forms)
- Capabilities-based guard (caps.rs) replacing role-id checks
- Mobile connector: message routing, payload types, router refactor
- Telegram bot: auth flow, event handling improvements
- Honcho plugin: substantial rework
- Sidebar: plugin pages integration, role-driven visibility
- i18n: new strings for plugins, connectors, capabilities
- Remove unused mascot asset

web/index.html

@@ -96,6 +96,10 @@
       <shared-folders-page></shared-folders-page>
       <connectors-page></connectors-page>
       <connector-detail-page></connector-detail-page>
+      <plugins-page></plugins-page>
+      <plugin-page-host></plugin-page-host>
+      <plugin-catalog-page></plugin-catalog-page>
+      <plugin-detail-page></plugin-detail-page>
       <marketplace-page></marketplace-page>
       <catalog-page></catalog-page>
       <profile-page style="display:none"></profile-page>