feat: auto-update outdated plugins at launch and add update UI in Settings

[datlechin]

Summary

• Outdated user-installed plugins are silently auto-updated from the registry at launch, eliminating the recurring "plugin(s) could not be loaded" error dialog
• When auto-update fails (no internet, plugin not in registry), the alert now has an actionable "Open Plugin Settings" button instead of just "OK"
• Settings > Plugins > Installed shows update badges and one-click "Update" button for plugins with newer registry versions
• Settings > Plugins > Browse shows "Update" button instead of "Installed" for outdated plugins

Test plan

• Place a .tableplugin with old TableProPluginKitVersion (e.g. 2) in ~/Library/Application Support/TablePro/Plugins/, launch app, verify no error dialog appears and plugin loads
• Disconnect internet, place old plugin, launch app, verify alert shows "Open Plugin Settings" + "Dismiss", clicking first button opens Settings at Plugins tab
• With an outdated user-installed plugin loaded, open Settings > Plugins > Installed, verify blue update badge in row and "Update" button in detail pane
• Open Settings > Plugins > Browse, verify outdated installed plugins show "Update" button instead of "Installed" text
• Launch with all plugins up to date, verify no change in behavior

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Preserve existing plugin until registry update succeeds

updateFromRegistry unloads/removes the currently loaded plugin before any download/verification/install work is attempted. If installFromRegistry then fails (for example, no network, non-2xx response, or checksum mismatch), the user is left without the previously working plugin in the current session because it has already been removed from plugins and capabilities were unregistered.

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[chatgpt-codex-connector]

Detect updates for installed theme plugins

hasUpdate(for:) only compares versions against pluginManager.plugins, but installed themes are not stored there (they are tracked by ThemeRegistryInstaller). As a result, outdated installed themes always evaluate as having no update, so Browse keeps showing "Installed" and never exposes the new update action for theme plugins.

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