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/styles/catppuccin.css

@@ -0,0 +1,52 @@
+/* Catppuccin Mocha — https://catppuccin.com/palette */
+:root {
+  --ctp-rosewater: #f5e0dc;
+  --ctp-flamingo: #f2cdcd;
+  --ctp-pink: #f5c2e7;
+  --ctp-mauve: #cba6f7;
+  --ctp-red: #f38ba8;
+  --ctp-maroon: #eba0ac;
+  --ctp-peach: #fab387;
+  --ctp-yellow: #f9e2af;
+  --ctp-green: #a6e3a1;
+  --ctp-teal: #94e2d5;
+  --ctp-sky: #89dceb;
+  --ctp-sapphire: #74c7ec;
+  --ctp-blue: #89b4fa;
+  --ctp-lavender: #b4befe;
+  --ctp-text: #cdd6f4;
+  --ctp-subtext1: #bac2de;
+  --ctp-subtext0: #a6adc8;
+  --ctp-overlay2: #9399b2;
+  --ctp-overlay1: #7f849c;
+  --ctp-overlay0: #6c7086;
+  --ctp-surface2: #585b70;
+  --ctp-surface1: #45475a;
+  --ctp-surface0: #313244;
+  --ctp-base: #1e1e2e;
+  --ctp-mantle: #181825;
+  --ctp-crust: #11111b;
+
+  /* Semantic aliases */
+  --bg-primary: var(--ctp-base);
+  --bg-secondary: var(--ctp-mantle);
+  --bg-tertiary: var(--ctp-crust);
+  --bg-surface: var(--ctp-surface0);
+  --bg-surface-hover: var(--ctp-surface1);
+  --text-primary: var(--ctp-text);
+  --text-secondary: var(--ctp-subtext1);
+  --text-muted: var(--ctp-overlay1);
+  --border: var(--ctp-surface1);
+  --accent: var(--ctp-blue);
+  --accent-hover: var(--ctp-sapphire);
+  --success: var(--ctp-green);
+  --warning: var(--ctp-yellow);
+  --error: var(--ctp-red);
+
+  /* Layout */
+  --sidebar-width: 260px;
+  --right-panel-width: 380px;
+  --pane-header-height: 32px;
+  --pane-gap: 2px;
+  --border-radius: 4px;
+}