feat(pro): wire all 7 Pro components into app

- ProjectBox: 5 Pro tabs (Analytics, Budget, Export, Symbols, Agent Mem)
  with PERSISTED-LAZY mount, proStatus() feature gate, peach accent color
- SettingsPanel: Pro tab (Accounts + Marketplace) conditionally shown
- ProSettings.svelte: wrapper with sub-tabs for AccountSwitcher + PluginMarketplace
- Feature detection via dynamic import of pro-bridge + proStatus() call
- All tabs hidden when agor-pro plugin not loaded (community edition)

src/lib/settings/settings-registry.ts

@@ -9,7 +9,8 @@ export type SettingsCategory =
   | 'security'
   | 'projects'
   | 'orchestration'
-  | 'advanced';
+  | 'advanced'
+  | 'pro';
 
 export interface SettingEntry {
   key: string;