feat: add tool framework foundation (types, registry, executor, shell tool, model types, SOUL.md)

- Task 0: SOUL.md + loadSystemPrompt() in daemon
- Task 1: Tool type definitions (Tool, ToolCall, ToolResult, etc.)
- Task 2: ToolRegistry with Anthropic/OpenAI serialization
- Task 3: ToolExecutor with hooks, timeout, truncation
- Task 4: shell.exec builtin tool
- Task 8: Model types updated for tool use (ToolDefinition, ModelToolCall, etc.)
- Task 15: Model index exports for tool types

src/models/types.test.ts

@@ -0,0 +1,52 @@
+import { describe, it, expect } from 'vitest';
+import type { ChatRequest, ChatResponse, ToolMessage, ContentBlock } from './types.js';
+
+describe('Model types with tool support', () => {
+  it('ChatRequest accepts tools array', () => {
+    const req: ChatRequest = {
+      messages: [{ role: 'user', content: 'hi' }],
+      tools: [{
+        name: 'test',
+        description: 'test tool',
+        input_schema: { type: 'object', properties: {} },
+      }],
+    };
+    expect(req.tools).toHaveLength(1);
+  });
+
+  it('ChatResponse has optional toolCalls', () => {
+    const resp: ChatResponse = {
+      content: '',
+      stopReason: 'tool_use',
+      usage: { inputTokens: 0, outputTokens: 0 },
+      toolCalls: [{ id: 'call_1', name: 'test', args: {} }],
+    };
+    expect(resp.toolCalls).toHaveLength(1);
+    expect(resp.stopReason).toBe('tool_use');
+  });
+
+  it('ChatResponse works without toolCalls (backward compatible)', () => {
+    const resp: ChatResponse = {
+      content: 'hello',
+      stopReason: 'end_turn',
+      usage: { inputTokens: 10, outputTokens: 5 },
+    };
+    expect(resp.toolCalls).toBeUndefined();
+  });
+
+  it('ToolMessage represents tool results in conversation', () => {
+    const msg: ToolMessage = {
+      role: 'tool_result',
+      toolResults: [{ tool_use_id: 'call_1', content: 'result', is_error: false }],
+    };
+    expect(msg.role).toBe('tool_result');
+    expect(msg.toolResults).toHaveLength(1);
+  });
+
+  it('ContentBlock can be text or tool_use', () => {
+    const text: ContentBlock = { type: 'text', text: 'hello' };
+    const tool: ContentBlock = { type: 'tool_use', id: 'c1', name: 'test', input: {} };
+    expect(text.type).toBe('text');
+    expect(tool.type).toBe('tool_use');
+  });
+});