feat: track received image outcomes

tests/repositories.test.ts

@@ -199,10 +199,12 @@ describe('MessagesRepository', () => {
     expect(row!.chatRoomId).toBe('!room123:reddit.com');
     expect(row!.recipient).toBe('alice');
     expect(row!.gotResponse).toBe(false);
+    expect(row!.gotImage).toBe(false);
 
-    messagesRepo.markGotResponse(id);
+    messagesRepo.markGotImage(id);
     const updated = messagesRepo.getByChatRoomId('!room123:reddit.com');
     expect(updated!.gotResponse).toBe(true);
+    expect(updated!.gotImage).toBe(true);
   });
 
   it('keeps unassociated chat history out of performance trends', () => {
@@ -353,6 +355,7 @@ describe('MessagesRepository', () => {
 
     messagesRepo.markGotResponse(1);
     messagesRepo.markGotResponse(3);
+    messagesRepo.markGotImage(1);
 
     const stats = messagesRepo.getStrategyStats();
     expect(stats.length).toBe(2);
@@ -361,11 +364,15 @@ describe('MessagesRepository', () => {
     expect(variantA!.totalSent).toBe(2);
     expect(variantA!.totalResponses).toBe(1);
     expect(variantA!.responseRate).toBe(50);
+    expect(variantA!.totalImages).toBe(1);
+    expect(variantA!.imageRate).toBe(50);
 
     const variantB = stats.find(s => s.strategyId === 'variant-b');
     expect(variantB!.totalSent).toBe(1);
     expect(variantB!.totalResponses).toBe(1);
     expect(variantB!.responseRate).toBe(100);
+    expect(variantB!.totalImages).toBe(0);
+    expect(variantB!.imageRate).toBe(0);
   });
 
   it('excludes messages without strategy_id from stats', () => {