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.css

@@ -0,0 +1,61 @@
+@import './lib/styles/catppuccin.css';
+
+*,
+*::before,
+*::after {
+  box-sizing: border-box;
+  margin: 0;
+  padding: 0;
+}
+
+html, body {
+  height: 100%;
+  width: 100%;
+  overflow: hidden;
+  background: var(--bg-primary);
+  color: var(--text-primary);
+  font-family: 'JetBrains Mono', 'Fira Code', 'Cascadia Code', monospace;
+  font-size: 13px;
+  line-height: 1.4;
+  -webkit-font-smoothing: antialiased;
+}
+
+#app {
+  height: 100%;
+  width: 100%;
+  display: grid;
+  grid-template-columns: var(--sidebar-width) 1fr;
+  grid-template-rows: 1fr;
+}
+
+/* Ultrawide: show right panel */
+@media (min-width: 3440px) {
+  #app {
+    grid-template-columns: var(--sidebar-width) 1fr var(--right-panel-width);
+  }
+}
+
+/* Narrow: collapse sidebar to icons */
+@media (max-width: 1200px) {
+  #app {
+    grid-template-columns: 48px 1fr;
+  }
+}
+
+::-webkit-scrollbar {
+  width: 6px;
+  height: 6px;
+}
+
+::-webkit-scrollbar-track {
+  background: var(--bg-secondary);
+}
+
+::-webkit-scrollbar-thumb {
+  background: var(--ctp-surface2);
+  border-radius: 3px;
+}
+
+::-webkit-scrollbar-thumb:hover {
+  background: var(--ctp-overlay0);
+}