feat(skills): add image vision skill for WhatsApp (#770)

* chore: prepare image-vision skill for template regeneration

- Delete stale modify/*.ts templates (built against 1.1.2)
- Update core_version to 1.2.6
- Strip fork-specific details from intent docs

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat(skills): regenerate image-vision modify/ templates against upstream

Templates regenerated against upstream 1.2.6:
- src/container-runner.ts: imageAttachments field in ContainerInput
- src/index.ts: parseImageReferences + threading to runAgent
- src/channels/whatsapp.ts: downloadMediaMessage + image handling block
- src/channels/whatsapp.test.ts: image mocks + 4 test cases
- container/agent-runner/src/index.ts: ContentBlock types, pushMultimodal, image loading

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* test: update image-vision tests for upstream templates

- Relax downloadMediaMessage import pattern check (multi-line import)
- Remove check for [Image - processing failed] (not in upstream template)
- Add vitest.skills.config.ts for skill package test runs

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* chore: update image-vision core_version to 1.2.8

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

.claude/skills/add-image-vision/add/src/image.test.ts

@@ -0,0 +1,89 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import fs from 'fs';
+
+// Mock sharp
+vi.mock('sharp', () => {
+  const mockSharp = vi.fn(() => ({
+    resize: vi.fn().mockReturnThis(),
+    jpeg: vi.fn().mockReturnThis(),
+    toBuffer: vi.fn().mockResolvedValue(Buffer.from('resized-image-data')),
+  }));
+  return { default: mockSharp };
+});
+
+vi.mock('fs');
+
+import { processImage, parseImageReferences, isImageMessage } from './image.js';
+
+describe('image processing', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    vi.mocked(fs.mkdirSync).mockReturnValue(undefined);
+    vi.mocked(fs.writeFileSync).mockReturnValue(undefined);
+  });
+
+  describe('isImageMessage', () => {
+    it('returns true for image messages', () => {
+      const msg = { message: { imageMessage: { mimetype: 'image/jpeg' } } };
+      expect(isImageMessage(msg as any)).toBe(true);
+    });
+
+    it('returns false for non-image messages', () => {
+      const msg = { message: { conversation: 'hello' } };
+      expect(isImageMessage(msg as any)).toBe(false);
+    });
+
+    it('returns false for null message', () => {
+      const msg = { message: null };
+      expect(isImageMessage(msg as any)).toBe(false);
+    });
+  });
+
+  describe('processImage', () => {
+    it('resizes and saves image, returns content string', async () => {
+      const buffer = Buffer.from('raw-image-data');
+      const result = await processImage(buffer, '/tmp/groups/test', 'Check this out');
+
+      expect(result).not.toBeNull();
+      expect(result!.content).toMatch(/^\[Image: attachments\/img-\d+-[a-z0-9]+\.jpg\] Check this out$/);
+      expect(result!.relativePath).toMatch(/^attachments\/img-\d+-[a-z0-9]+\.jpg$/);
+      expect(fs.mkdirSync).toHaveBeenCalled();
+      expect(fs.writeFileSync).toHaveBeenCalled();
+    });
+
+    it('returns content without caption when none provided', async () => {
+      const buffer = Buffer.from('raw-image-data');
+      const result = await processImage(buffer, '/tmp/groups/test', '');
+
+      expect(result).not.toBeNull();
+      expect(result!.content).toMatch(/^\[Image: attachments\/img-\d+-[a-z0-9]+\.jpg\]$/);
+    });
+
+    it('returns null on empty buffer', async () => {
+      const result = await processImage(Buffer.alloc(0), '/tmp/groups/test', '');
+
+      expect(result).toBeNull();
+    });
+  });
+
+  describe('parseImageReferences', () => {
+    it('extracts image paths from message content', () => {
+      const messages = [
+        { content: '[Image: attachments/img-123.jpg] hello' },
+        { content: 'plain text' },
+        { content: '[Image: attachments/img-456.jpg]' },
+      ];
+      const refs = parseImageReferences(messages as any);
+
+      expect(refs).toEqual([
+        { relativePath: 'attachments/img-123.jpg', mediaType: 'image/jpeg' },
+        { relativePath: 'attachments/img-456.jpg', mediaType: 'image/jpeg' },
+      ]);
+    });
+
+    it('returns empty array when no images', () => {
+      const messages = [{ content: 'just text' }];
+      expect(parseImageReferences(messages as any)).toEqual([]);
+    });
+  });
+});