fix: resolve CI test failures by removing unused imports and updating workflow paths

- Created models.py with HistoryEntry and SearchResult classes
- Created database.py with Database wrapper class
- Fixed test files to use actual implementation APIs
- Fixed conftest.py SearchResult fixture field names

tests/conftest.py

@@ -20,9 +20,10 @@ def sample_history_entry():
 def sample_search_result():
     return SearchResult(
         command="ls -la",
-        timestamp=1234567890.0,
-        score=0.95,
-        shell="bash"
+        shell_type="bash",
+        timestamp=1234567890,
+        similarity=0.95,
+        command_id=1
     )