refactor(electrobun): centralize all shared state into global stores

New stores:
- ui-store.svelte.ts: settingsOpen, paletteOpen, searchOpen, notifDrawerOpen,
  showWizard, settingsCategory, projectToDelete, showAddGroup, newGroupName
- project-tabs-store.svelte.ts: per-project activeTab + activatedTabs via Map

Wired:
- App.svelte: 8 inline $state removed, reads/writes via ui-store
- ProjectCard: activeTab/activatedTabs from project-tabs-store
- SettingsDrawer: activeCategory from ui-store
- CommandPalette: 4 commands call ui-store directly (no CustomEvent dispatch)

Components are now pure view layers reading from stores.

ui-electrobun/src/mainview/ProjectCard.svelte

@@ -13,8 +13,10 @@
     loadLastSession,
     type AgentStatus, type AgentMessage,
   } from './agent-store.svelte.ts';
-
-  type ProjectTab = 'model' | 'docs' | 'context' | 'files' | 'ssh' | 'memory' | 'comms' | 'tasks';
+  import {
+    getActiveTab, setActiveTab, isTabActivated,
+    ALL_TABS, type ProjectTab,
+  } from './project-tabs-store.svelte.ts';
 
   interface Props {
     id: string;
@@ -117,11 +119,8 @@
     showCloneDialog = false;
   }
 
-  let activeTab = $state<ProjectTab>('model');
-  // Track which project tabs have been activated (PERSISTED-LAZY pattern)
-  let activatedTabs = $state<Set<ProjectTab>>(new Set(['model']));
-
-  const ALL_TABS: ProjectTab[] = ['model', 'docs', 'context', 'files', 'ssh', 'memory', 'comms', 'tasks'];
+  // Derived from project-tabs-store for reactive reads
+  let activeTab = $derived(getActiveTab(id));
 
   // ── Load last session on mount ──────────────────────────────────────
   $effect(() => {
@@ -129,8 +128,7 @@
   });
 
   function setTab(tab: ProjectTab) {
-    activeTab = tab;
-    activatedTabs = new Set([...activatedTabs, tab]);
+    setActiveTab(id, tab);
   }
 
   function handleSend(text: string) {