feat(v3): implement Mission Control MVP (Phases 1-5)

Phase 1: Data model - groups.rs (Rust structs + load/save groups.json),
groups.ts (TypeScript interfaces), groups-bridge.ts (IPC adapter),
workspace.svelte.ts (replaces layout store), SQLite migrations
(agent_messages, project_agent_state tables, project_id column),
--group CLI argument.

Phase 2: Project shell layout - GlobalTabBar, ProjectGrid, ProjectBox,
ProjectHeader, CommandPalette, DocsTab, ContextTab, SettingsTab,
App.svelte full rewrite (no sidebar/TilingGrid).

Phase 3: ClaudeSession.svelte wrapping AgentPane per-project.
Phase 4: TerminalTabs.svelte with shell/SSH/agent tab types.
Phase 5: TeamAgentsPanel + AgentCard for compact subagent view.

Also fixes AgentPane Svelte 5 event modifier (on:click -> onclick).

v2/src/lib/components/Workspace/GlobalTabBar.svelte

@@ -0,0 +1,56 @@
+<script lang="ts">
+  import { getActiveTab, setActiveTab, type WorkspaceTab } from '../../stores/workspace.svelte';
+
+  const tabs: { id: WorkspaceTab; label: string; shortcut: string }[] = [
+    { id: 'sessions', label: 'Sessions', shortcut: 'Alt+1' },
+    { id: 'docs', label: 'Docs', shortcut: 'Alt+2' },
+    { id: 'context', label: 'Context', shortcut: 'Alt+3' },
+    { id: 'settings', label: 'Settings', shortcut: 'Alt+4' },
+  ];
+</script>
+
+<nav class="global-tab-bar">
+  {#each tabs as tab}
+    <button
+      class="tab-btn"
+      class:active={getActiveTab() === tab.id}
+      onclick={() => setActiveTab(tab.id)}
+      title={tab.shortcut}
+    >
+      {tab.label}
+    </button>
+  {/each}
+</nav>
+
+<style>
+  .global-tab-bar {
+    display: flex;
+    gap: 2px;
+    padding: 4px 8px;
+    background: var(--ctp-mantle);
+    border-bottom: 1px solid var(--ctp-surface0);
+    flex-shrink: 0;
+  }
+
+  .tab-btn {
+    padding: 4px 14px;
+    background: transparent;
+    border: none;
+    color: var(--ctp-subtext0);
+    font-size: 0.8rem;
+    cursor: pointer;
+    border-radius: 4px 4px 0 0;
+    transition: color 0.15s, background 0.15s;
+  }
+
+  .tab-btn:hover {
+    color: var(--ctp-text);
+    background: var(--ctp-surface0);
+  }
+
+  .tab-btn.active {
+    color: var(--ctp-text);
+    background: var(--ctp-base);
+    border-bottom: 2px solid var(--ctp-blue);
+  }
+</style>