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

src/shell_history_search/database.py

@@ -0,0 +1,51 @@
+import sqlite3
+from pathlib import Path
+from typing import Optional
+
+from .db import init_database
+
+
+class Database:
+    def __init__(self, db_path: str):
+        self._db_path = Path(db_path)
+        self._conn: Optional[sqlite3.Connection] = None
+
+    def _ensure_connection(self) -> sqlite3.Connection:
+        if self._conn is None:
+            self._conn = init_database(self._db_path)
+        return self._conn
+
+    def add_entry(self, entry) -> None:
+        conn = self._ensure_connection()
+        if hasattr(entry, 'command_hash'):
+            command_hash = entry.command_hash
+        else:
+            import hashlib
+            command_hash = hashlib.sha256(entry.command.encode()).hexdigest()[:16]
+
+        timestamp = int(entry.timestamp) if hasattr(entry, 'timestamp') and entry.timestamp else None
+        shell_type = getattr(entry, 'shell', getattr(entry, 'shell_type', 'unknown'))
+        hostname = getattr(entry, 'working_dir', getattr(entry, 'hostname', None))
+
+        conn.execute(
+            """
+            INSERT OR IGNORE INTO commands (command, shell_type, timestamp, hostname, command_hash)
+            VALUES (?, ?, ?, ?, ?)
+            """,
+            (entry.command, shell_type, timestamp, hostname, command_hash),
+        )
+        conn.commit()
+
+    def get_connection(self) -> sqlite3.Connection:
+        return self._ensure_connection()
+
+    def close(self) -> None:
+        if self._conn:
+            self._conn.close()
+            self._conn = None
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.close()