feat: Refactor Fund schema to use many-to-many relationships for investment stages and sectors

- Updated FundTable to replace JSON fields for investment stages and sectors with relationships.
- Introduced InvestmentStageTable and fund_investment_stages association table.
- Created fund_sectors association table for many-to-many relationship with sectors.
- Changed geographic_focus from JSON array to a simple string.
- Migrated existing data to new schema, ensuring data integrity and normalization.
- Updated related schemas, routers, and services to reflect new structure.
- Added migration script to handle data transformation and schema updates.
- Implemented tests to verify new relationships and data integrity.

app/schemas/router_schemas.py

@@ -22,6 +22,14 @@ class SectorSchema(BaseModel):
         from_attributes = True
 
 
+class InvestmentStageSchema(BaseModel):
+    id: int
+    name: str
+
+    class Config:
+        from_attributes = True
+
+
 class InvestorMemberSchema(BaseModel):
     id: int
     name: str
@@ -41,9 +49,9 @@ class FundSchema(BaseModel):
     check_size_upper: int | None  # NEW: Upper bound of check size range
     source_url: str | None
     source_provider: str | None
-    geographic_focus: List[str] | None
-    investment_stage_focus: List[str] | None
-    sector_focus: List[str] | None
+    geographic_focus: str | None  # Changed from List[str] to string
+    investment_stages: List[InvestmentStageSchema] | None  # Changed to relationship
+    sectors: List[SectorSchema] | None  # Changed to relationship
     created_at: Optional[datetime] = None
     updated_at: Optional[datetime] = None
 
@@ -134,9 +142,11 @@ class InvestorFundData(BaseModel):
     fund_size_source_url: str | None
     check_size_lower: int | None  # NEW: Lower bound of check size range
     check_size_upper: int | None  # NEW: Upper bound of check size range
-    geographic_focus: List[str] | None
-    investment_stage_focus: List[str] | None
-    sector_focus: List[str] | None
+    geographic_focus: str | None  # Changed from List[str] to string
+    fund_investment_stages: (
+        List[InvestmentStageSchema] | None
+    )  # Changed to relationship
+    fund_sectors: List[SectorSchema] | None  # Changed to relationship
 
     # Related data
     portfolio_companies: List[CompanySchema]