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/sidecar/agent-runner.ts

@@ -0,0 +1,42 @@
+// Agent Runner — Node.js sidecar entry point
+// Spawned by Rust backend, communicates via stdio NDJSON
+// Phase 3: full Agent SDK integration
+
+import { stdin, stdout, stderr } from 'process';
+import { createInterface } from 'readline';
+
+const rl = createInterface({ input: stdin });
+
+function send(msg: Record<string, unknown>) {
+  stdout.write(JSON.stringify(msg) + '\n');
+}
+
+function log(message: string) {
+  stderr.write(`[sidecar] ${message}\n`);
+}
+
+rl.on('line', (line: string) => {
+  try {
+    const msg = JSON.parse(line);
+    handleMessage(msg);
+  } catch {
+    log(`Invalid JSON: ${line}`);
+  }
+});
+
+function handleMessage(msg: Record<string, unknown>) {
+  switch (msg.type) {
+    case 'ping':
+      send({ type: 'pong' });
+      break;
+    case 'query':
+      // Phase 3: call Agent SDK query()
+      send({ type: 'error', message: 'Agent SDK not yet integrated — Phase 3' });
+      break;
+    default:
+      send({ type: 'error', message: `Unknown message type: ${msg.type}` });
+  }
+}
+
+log('Sidecar started');
+send({ type: 'ready' });

v2/sidecar/package.json

@@ -0,0 +1,12 @@
+{
+  "name": "bterminal-sidecar",
+  "private": true,
+  "version": "0.1.0",
+  "type": "module",
+  "scripts": {
+    "build": "esbuild agent-runner.ts --bundle --platform=node --target=node20 --outfile=dist/agent-runner.mjs --format=esm"
+  },
+  "devDependencies": {
+    "esbuild": "0.25.4"
+  }
+}