docs: Add docstrings for the store manager and main

Refs: OPS-68

senju/store_manager.py

@@ -25,13 +25,43 @@ class StoreManager:
     logger: Logger
 
     def __init__(self, path_to_db: Path = DEFAULT_DB_PATH) -> None:
+        """
+        Initialize the StoreManager with a database path.
+
+        Args:
+            path_to_db (Path, optional): Path to the TinyDB database file.
+                Defaults to DEFAULT_DB_PATH.
+        """
         self._db = TinyDB(path_to_db)
         self.logger = Logger(__name__)
 
     def _query(self, query: QueryImpl) -> list[dict]:
+        """
+        Execute a query against the database.
+
+        Args:
+            query (QueryImpl): TinyDB query to execute.
+
+        Returns:
+            list[dict]: List of documents matching the query.
+        """
+
         return self._db.search(query)
 
     def _load(self, id: int) -> Optional[dict]:
+        """
+        Load a document by its ID.
+
+        Args:
+            id (int): Document ID to load.
+
+        Returns:
+            Optional[dict]: The document if found, None otherwise.
+
+        Logs:
+            Warning if document with specified ID is not found.
+        """
+
         try:
             return self._db.get(doc_id=id)
         except IndexError as e:
@@ -39,9 +69,29 @@ class StoreManager:
             return None
 
     def _save(self, data: dict) -> int:
+        """
+        Save a document to the database.
+
+        Args:
+            data (dict): Document data to save.
+
+        Returns:
+            int: The document ID of the saved document.
+        """
+
         return self._db.insert(data)
 
     def load_haiku(self, key: int) -> Optional[Haiku]:
+        """
+        Load a haiku by its ID.
+
+        Args:
+            key (int): The ID of the haiku to load.
+
+        Returns:
+            Optional[Haiku]: A Haiku object if found, None otherwise.
+        """
+
         raw_haiku: dict | None = self._load(key)
         if raw_haiku is None:
             return None
@@ -49,9 +99,29 @@ class StoreManager:
         return h
 
     def save_haiku(self, data: Haiku) -> int:
+        """
+        Save a haiku to the database.
+
+        Args:
+            data (Haiku): The Haiku object to save.
+
+        Returns:
+            int: The document ID of the saved haiku.
+        """
+
         return self._save(data.__dict__)
 
     def get_id_of_latest_haiku(self) -> Optional[int]:
+        """
+        Get the ID of the most recently added haiku.
+
+        Returns:
+            Optional[int]: The ID of the latest haiku if any exists, None otherwise.
+
+        Logs:
+            Error if the database is empty.
+        """
+
         try:
             id = self._db.all()[-1].doc_id
             return id