feat: introduce post resource with full CRUD operations and generation linking.

api/models/PostRequest.py

@@ -0,0 +1,19 @@
+from datetime import datetime
+from typing import Optional, List
+from pydantic import BaseModel
+
+
+class PostCreateRequest(BaseModel):
+    date: datetime
+    topic: str
+    generation_ids: List[str] = []
+    project_id: Optional[str] = None
+
+
+class PostUpdateRequest(BaseModel):
+    date: Optional[datetime] = None
+    topic: Optional[str] = None
+
+
+class AddGenerationsRequest(BaseModel):
+    generation_ids: List[str]