refactor: migrate to Turborepo + pnpm + Biome monorepo

Restructure into apps/worker, apps/cli, packages/mcp-server with
Turborepo task orchestration, pnpm workspaces, Biome linting/formatting,
and tsdown CLI bundling.

Key changes:
- src/ -> apps/worker/src/, cli/ -> apps/cli/, mcp-server/ -> packages/mcp-server/
- prompts/ and configs/ moved into apps/worker/
- npm replaced with pnpm, package-lock.json replaced with pnpm-lock.yaml
- Dockerfile updated for pnpm-based builds
- CLI logs command rewritten with chokidar for cross-platform reliability
- Router health checking added for auto-detected router mode
- Centralized path resolution via apps/worker/src/paths.ts

apps/cli/src/commands/workspaces.ts

@@ -0,0 +1,34 @@
+/**
+ * `shannon workspaces` command — list all workspaces.
+ */
+
+import { execFileSync } from 'node:child_process';
+import { getWorkerImage } from '../docker.js';
+import { getWorkspacesDir } from '../home.js';
+
+export function workspaces(version: string): void {
+  const workspacesDir = getWorkspacesDir();
+  const image = getWorkerImage(version);
+
+  try {
+    execFileSync(
+      'docker',
+      [
+        'run',
+        '--rm',
+        '-v',
+        `${workspacesDir}:/app/workspaces`,
+        '-e',
+        'WORKSPACES_DIR=/app/workspaces',
+        image,
+        'node',
+        'apps/worker/dist/temporal/workspaces.js',
+      ],
+      { stdio: 'inherit' },
+    );
+  } catch {
+    console.error('ERROR: Failed to list workspaces. Is the Docker image available?');
+    console.error(`  Run: docker pull ${image}`);
+    process.exit(1);
+  }
+}