Implemented directory management and improved TravelDiary and Photo handling logic.

- Added `DirectoryManager` utility for consistent directory operations.
- Introduced directory name sanitization and uniqueness enforcement for `TravelDiary`.
- Updated `TravelDiaryService` with enhanced creation, update, and deletion workflows, including filesystem management.
- Improved `PhotoService` to hash files, copy photos to specific diary directories, and manage updates safely.
- Refined error handling and cascaded changes across related entities (e.g., `Entry` relationships).

src/pilgrim/models/entry.py

@@ -1,9 +1,9 @@
 from typing import Any
 
+from pilgrim.models.photo_in_entry import photo_entry_association
 from sqlalchemy import Column, Integer, String, ForeignKey, DateTime
 from sqlalchemy.orm import relationship
 
-from pilgrim.models.photo_in_entry import photo_entry_association
 from ..database import Base
 
 
@@ -17,7 +17,9 @@ class Entry(Base):
         "Photo",
         secondary=photo_entry_association,
         back_populates="entries")
-    fk_travel_diary_id = Column(Integer, ForeignKey("travel_diaries.id"),nullable=False)
+    fk_travel_diary_id = Column(Integer, ForeignKey("travel_diaries.id"), nullable=False)
+    travel_diary = relationship("TravelDiary", back_populates="entries")
+
     def __init__(self, title: str, text: str, date: str, travel_diary_id: int, **kw: Any):
         super().__init__(**kw)
         self.title = title