feat: Add organization member support with memberType field

Implements support for both individual persons and organizations as members.

Changes:
- Added MemberType enum (INDIVIDUAL, ORGANIZATION) to distinguish member types
- Added member_type column to database (defaults to INDIVIDUAL for backward compatibility)
- Added company_name field for organizations
- Made first_name nullable (required for individuals, optional for organizations)
- Implemented conditional validation:
  - INDIVIDUAL members require first_name
  - ORGANIZATION members require company_name
- Updated GraphQL schema with new memberType and companyName fields
- Updated all resolvers to handle new fields and validation
- Added comprehensive unit tests for validation logic
- Updated existing tests to work with new fields
- All 53 tests passing

Technical notes:
- Using memberType instead of 'kind' to avoid GraphQL introspection conflicts
- Using native_enum=False for SQLite compatibility
- Using batch_alter_table for SQLite ALTER COLUMN compatibility
- Backward compatible: existing members automatically become INDIVIDUAL type

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/resolvers/member.py

@@ -6,7 +6,7 @@ from sqlalchemy import select
 from src.database import async_session_maker
 from src.models.member import Member as MemberModel
 from src.schemas.member import CreateMemberInput, Member, UpdateMemberInput
-from src.validation import validate_email, validate_first_name, validate_phone
+from src.validation import validate_email, validate_phone, validate_member_type_requirements
 
 
 class MemberNotFoundError(Exception):
@@ -31,7 +31,9 @@ class Query:
 
             return Member(
                 id=db_member.id,
+                member_type=db_member.member_type,
                 first_name=db_member.first_name,
+                company_name=db_member.company_name,
                 last_name=db_member.last_name,
                 street=db_member.street,
                 apartment_number=db_member.apartment_number,
@@ -58,7 +60,9 @@ class Query:
             return [
                 Member(
                     id=m.id,
+                    member_type=m.member_type,
                     first_name=m.first_name,
+                    company_name=m.company_name,
                     last_name=m.last_name,
                     street=m.street,
                     apartment_number=m.apartment_number,
@@ -79,8 +83,12 @@ class Mutation:
     @strawberry.mutation
     async def create_member(self, input: CreateMemberInput) -> Member:
         """Create a new member with validation."""
-        # Validate required field
-        validate_first_name(input.first_name)
+        # Validate conditional requirements based on member type
+        validate_member_type_requirements(
+            member_type=input.member_type.value,
+            first_name=input.first_name,
+            company_name=input.company_name
+        )
 
         # Conditional validation (only if fields are provided)
         validate_email(input.email)
@@ -89,7 +97,9 @@ class Mutation:
         async with async_session_maker() as session:
             # Create new member
             db_member = MemberModel(
+                member_type=input.member_type,
                 first_name=input.first_name,
+                company_name=input.company_name,
                 last_name=input.last_name,
                 street=input.street,
                 apartment_number=input.apartment_number,
@@ -106,7 +116,9 @@ class Mutation:
 
             return Member(
                 id=db_member.id,
+                member_type=db_member.member_type,
                 first_name=db_member.first_name,
+                company_name=db_member.company_name,
                 last_name=db_member.last_name,
                 street=db_member.street,
                 apartment_number=db_member.apartment_number,
@@ -132,15 +144,29 @@ class Mutation:
             if db_member is None:
                 raise MemberNotFoundError(f"Member with ID {input.id} not found")
 
-            # Validate if fields are being updated
-            if input.first_name is not None:
-                validate_first_name(input.first_name)
+            # Determine final values for validation (combining existing and new values)
+            final_member_type = input.member_type.value if input.member_type is not None else db_member.member_type.value
+            final_first_name = input.first_name if input.first_name is not None else db_member.first_name
+            final_company_name = input.company_name if input.company_name is not None else db_member.company_name
+
+            # Validate conditional requirements with final values
+            validate_member_type_requirements(
+                member_type=final_member_type,
+                first_name=final_first_name,
+                company_name=final_company_name
+            )
+
+            # Conditional validation (only if fields are provided)
             validate_email(input.email)
             validate_phone(input.phone)
 
             # Update fields if provided
+            if input.member_type is not None:
+                db_member.member_type = input.member_type
             if input.first_name is not None:
                 db_member.first_name = input.first_name
+            if input.company_name is not None:
+                db_member.company_name = input.company_name
             if input.last_name is not None:
                 db_member.last_name = input.last_name
             if input.street is not None:
@@ -163,7 +189,9 @@ class Mutation:
 
             return Member(
                 id=db_member.id,
+                member_type=db_member.member_type,
                 first_name=db_member.first_name,
+                company_name=db_member.company_name,
                 last_name=db_member.last_name,
                 street=db_member.street,
                 apartment_number=db_member.apartment_number,