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/App.svelte

@@ -0,0 +1,27 @@
+<script lang="ts">
+  import SessionList from './lib/components/Sidebar/SessionList.svelte';
+  import TilingGrid from './lib/components/Layout/TilingGrid.svelte';
+</script>
+
+<aside class="sidebar">
+  <SessionList />
+</aside>
+<main class="workspace">
+  <TilingGrid />
+</main>
+
+<style>
+  .sidebar {
+    background: var(--bg-secondary);
+    border-right: 1px solid var(--border);
+    overflow-y: auto;
+    display: flex;
+    flex-direction: column;
+  }
+
+  .workspace {
+    background: var(--bg-primary);
+    overflow: hidden;
+    position: relative;
+  }
+</style>