* feat(extension): add PluginSortControl reusable component for sorting
* i18n: add i18n keys for plugin sorting and filtering features
* feat(extension): add sorting and status filtering for installed plugins
Backend changes (plugin.py):
- Add _resolve_plugin_dir method to resolve plugin directory path
- Add _get_plugin_installed_at method to get installation time from file mtime
- Add installed_at field to plugin API response
Frontend changes (InstalledPluginsTab.vue):
- Import PluginSortControl component
- Add status filter toggle (all/enabled/disabled) using v-btn-toggle
- Integrate PluginSortControl for sorting options
- Add toolbar layout with actions and controls sections
Frontend changes (MarketPluginsTab.vue):
- Import PluginSortControl component
- Replace v-select + v-btn combination with unified PluginSortControl
Frontend changes (useExtensionPage.js):
- Add installedStatusFilter, installedSortBy, installedSortOrder refs
- Add installedSortItems and installedSortUsesOrder computed properties
- Add sortInstalledPlugins function with multi-criteria support
- Support sorting by install time, name, author, and update status
- Add status filtering in filteredPlugins computed property
- Disable default table sorting by setting sortable: false
* test: add tests for installed_at field in plugin API
- Assert all plugins have installed_at field in get_plugins response
- Assert installed_at is not null after plugin installation
* fix(extension): add explicit fallbacks for installed plugin sort comparisons
* i18n(extension): rename install time label to last modified
* fix(extension): cache installed_at parsing and validate timestamp format in tests
* test(dashboard): strengthen installed_at coverage for plugin API
ChuwuYo