fix: update mock database schema to match conversation tracker queries

- Add missing columns: slug, model, conversation_count, total_messages, total_tokens, created_at, project_path
- Fix test data insert to include all required columns

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

dashboard/backend/tests/conftest.py

@@ -304,10 +304,12 @@ def mock_conversation_db(tmp_path, monkeypatch):
         CREATE TABLE conversations (
             session_id TEXT PRIMARY KEY,
             project_path TEXT,
+            slug TEXT,
             started_at DATETIME,
             message_count INTEGER,
             total_input_tokens INTEGER DEFAULT 0,
-            total_output_tokens INTEGER DEFAULT 0
+            total_output_tokens INTEGER DEFAULT 0,
+            model TEXT
         )
     """)
     conn.execute("""
@@ -332,14 +334,19 @@ def mock_conversation_db(tmp_path, monkeypatch):
         CREATE TABLE daily_summaries (
             id INTEGER PRIMARY KEY AUTOINCREMENT,
             date TEXT UNIQUE NOT NULL,
-            summary_content TEXT NOT NULL
+            summary_content TEXT NOT NULL,
+            conversation_count INTEGER DEFAULT 0,
+            total_messages INTEGER DEFAULT 0,
+            total_tokens INTEGER DEFAULT 0,
+            created_at DATETIME,
+            project_path TEXT
         )
     """)
 
     # Insert test data
     conn.execute("""
         INSERT INTO conversations VALUES
-        ('test-session-id', '/test/project', '2026-04-19 10:00:00', 10, 1000, 500)
+        ('test-session-id', '/test/project', 'test-slug', '2026-04-19 10:00:00', 10, 1000, 500, 'claude-sonnet-4')
     """)
     conn.execute("""
         INSERT INTO messages VALUES