feat(v2): scaffold Tauri 2.x + Svelte 5 project (Phase 1)

- Tauri 2.10 + Svelte 5.45 + TypeScript + Vite 7
- Catppuccin Mocha theme with CSS variables and semantic aliases
- CSS Grid layout: sidebar (260px) + workspace, responsive breakpoints
  for ultrawide (3440px+) and narrow (<1200px)
- Component structure: Layout/, Terminal/, Agent/, Markdown/, Sidebar/
- Svelte 5 stores with $state runes: sessions, agents, layout
- SDK message adapter (abstracts Agent SDK wire format)
- PTY bridge (Tauri IPC wrapper, stubbed for Phase 2)
- Node.js sidecar entry point (stdio NDJSON, stubbed for Phase 3)
- Rust modules: pty, sidecar, watcher, session (stubbed)
- Vite dev server on port 9700
- Build verified: binary + .deb + .rpm + AppImage all produced

v2/src/lib/components/Layout/PaneContainer.svelte

@@ -0,0 +1,54 @@
+<script lang="ts">
+  import type { Snippet } from 'svelte';
+
+  interface Props {
+    title: string;
+    children: Snippet;
+  }
+
+  let { title, children }: Props = $props();
+</script>
+
+<div class="pane-container">
+  <div class="pane-header">
+    <span class="pane-title">{title}</span>
+  </div>
+  <div class="pane-content">
+    {@render children()}
+  </div>
+</div>
+
+<style>
+  .pane-container {
+    display: flex;
+    flex-direction: column;
+    background: var(--bg-secondary);
+    border-radius: var(--border-radius);
+    overflow: hidden;
+    border: 1px solid var(--border);
+  }
+
+  .pane-header {
+    height: var(--pane-header-height);
+    display: flex;
+    align-items: center;
+    padding: 0 10px;
+    background: var(--bg-tertiary);
+    border-bottom: 1px solid var(--border);
+    flex-shrink: 0;
+  }
+
+  .pane-title {
+    font-size: 12px;
+    font-weight: 500;
+    color: var(--text-secondary);
+    white-space: nowrap;
+    overflow: hidden;
+    text-overflow: ellipsis;
+  }
+
+  .pane-content {
+    flex: 1;
+    overflow: auto;
+  }
+</style>

v2/src/lib/components/Layout/PaneHeader.svelte

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+<script lang="ts">
+  interface Props {
+    title: string;
+    status?: 'idle' | 'running' | 'error' | 'done';
+  }
+
+  let { title, status = 'idle' }: Props = $props();
+</script>
+
+<div class="pane-header">
+  <span class="pane-title">{title}</span>
+  {#if status !== 'idle'}
+    <span class="status-indicator {status}">{status}</span>
+  {/if}
+</div>
+
+<style>
+  .pane-header {
+    height: var(--pane-header-height);
+    display: flex;
+    align-items: center;
+    justify-content: space-between;
+    padding: 0 10px;
+    background: var(--bg-tertiary);
+    border-bottom: 1px solid var(--border);
+    flex-shrink: 0;
+  }
+
+  .pane-title {
+    font-size: 12px;
+    font-weight: 500;
+    color: var(--text-secondary);
+  }
+
+  .status-indicator {
+    font-size: 10px;
+    padding: 2px 6px;
+    border-radius: 3px;
+  }
+
+  .status-indicator.running { color: var(--ctp-blue); }
+  .status-indicator.error { color: var(--ctp-red); }
+  .status-indicator.done { color: var(--ctp-green); }
+</style>

v2/src/lib/components/Layout/TilingGrid.svelte

@@ -0,0 +1,58 @@
+<script lang="ts">
+  import PaneContainer from './PaneContainer.svelte';
+
+  // Phase 2: dynamic pane management, resize, presets
+  // For now: single empty pane as placeholder
+</script>
+
+<div class="tiling-grid">
+  <PaneContainer title="Welcome">
+    <div class="welcome">
+      <h1>BTerminal v2</h1>
+      <p>Claude Agent Mission Control</p>
+      <div class="status">
+        <span class="badge">Phase 1 — Scaffold</span>
+      </div>
+    </div>
+  </PaneContainer>
+</div>
+
+<style>
+  .tiling-grid {
+    display: grid;
+    grid-template-columns: 1fr;
+    grid-template-rows: 1fr;
+    gap: var(--pane-gap);
+    height: 100%;
+    padding: var(--pane-gap);
+  }
+
+  .welcome {
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+    justify-content: center;
+    height: 100%;
+    gap: 8px;
+    color: var(--text-muted);
+  }
+
+  .welcome h1 {
+    font-size: 24px;
+    font-weight: 700;
+    color: var(--text-primary);
+  }
+
+  .welcome p {
+    font-size: 14px;
+  }
+
+  .badge {
+    background: var(--bg-surface);
+    color: var(--accent);
+    padding: 4px 12px;
+    border-radius: var(--border-radius);
+    font-size: 12px;
+    margin-top: 8px;
+  }
+</style>

v2/src/lib/components/Sidebar/SessionList.svelte

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+<script lang="ts">
+  // Phase 4: session CRUD, groups, types
+</script>
+
+<div class="session-list">
+  <div class="header">
+    <h2>Sessions</h2>
+  </div>
+  <div class="empty-state">
+    <p>No sessions yet.</p>
+    <p class="hint">Phase 2 will add terminal sessions.</p>
+  </div>
+</div>
+
+<style>
+  .session-list {
+    padding: 12px;
+  }
+
+  .header h2 {
+    font-size: 14px;
+    font-weight: 600;
+    color: var(--text-primary);
+    margin-bottom: 12px;
+  }
+
+  .empty-state {
+    color: var(--text-muted);
+    font-size: 12px;
+    text-align: center;
+    padding: 24px 0;
+  }
+
+  .hint {
+    margin-top: 4px;
+    font-size: 11px;
+    color: var(--ctp-overlay0);
+  }
+</style>