feat: add plan2code-bot with --resume capability and state cleanup

Add the autonomous workflow test runner (plan2code-bot) that uses the
Claude Agent SDK to run plan2code end-to-end. Includes --resume flag
to continue incomplete runs from saved state, and automatic state file
cleanup on successful completion.

plan2code-bot/src/prompts/step-instructions.test.ts

@@ -0,0 +1,58 @@
+import { describe, it, expect } from 'vitest';
+import { buildStepPrompt } from './step-instructions.js';
+import type { BotConfig } from '../types.js';
+
+const config: BotConfig = {
+  workDir: '/tmp/work',
+  projectDir: '/tmp/work/my-app',
+  ideaDescription: 'A todo app with drag-and-drop',
+  ideaName: 'drag-todo',
+  mode: 'new-project',
+};
+
+describe('buildStepPrompt', () => {
+  it('each step includes the autonomous preamble', () => {
+    const steps = ['init', 'plan', 'document', 'implement', 'finalize'] as const;
+    for (const step of steps) {
+      const prompt = buildStepPrompt(step, config);
+      expect(prompt).toContain('running autonomously');
+    }
+  });
+
+  it('init prompt includes /plan2code-init skill invocation', () => {
+    const prompt = buildStepPrompt('init', config);
+    expect(prompt).toContain('/plan2code-init');
+  });
+
+  it('plan prompt includes /plan2code-1-plan skill invocation', () => {
+    const prompt = buildStepPrompt('plan', config);
+    expect(prompt).toContain('/plan2code-1-plan');
+  });
+
+  it('document prompt includes /plan2code-2-document skill invocation', () => {
+    const prompt = buildStepPrompt('document', config);
+    expect(prompt).toContain('/plan2code-2-document');
+  });
+
+  it('implement prompt includes /plan2code-3-implement skill invocation', () => {
+    const prompt = buildStepPrompt('implement', config);
+    expect(prompt).toContain('/plan2code-3-implement');
+  });
+
+  it('finalize prompt includes /plan2code-4-finalize skill invocation', () => {
+    const prompt = buildStepPrompt('finalize', config);
+    expect(prompt).toContain('/plan2code-4-finalize');
+  });
+
+  it('plan prompt includes project name and description', () => {
+    const prompt = buildStepPrompt('plan', config);
+    expect(prompt).toContain('drag-todo');
+    expect(prompt).toContain('A todo app with drag-and-drop');
+  });
+
+  it('init prompt includes project name and description', () => {
+    const prompt = buildStepPrompt('init', config);
+    expect(prompt).toContain('drag-todo');
+    expect(prompt).toContain('A todo app with drag-and-drop');
+  });
+});