feat: implement GraphQL member management API

Implement complete member management system with GraphQL API per OpenSpec proposal.
Only firstName is required; all other fields are optional with conditional validation.

Key features:
- GraphQL CRUD operations (create, read, update, delete members)
- SQLAlchemy 2.0 async with SQLite database
- Alembic database migrations
- Conditional validation (email/phone validated only when provided)
- Member fields: firstName (required), lastName, address, email, phone (all optional)
- Database seed script with sample member
- FastAPI with Strawberry GraphQL integration

Implementation details:
- Python 3.11+ with uv package manager
- Async database sessions throughout
- Proper error handling and validation
- Code quality: black, isort, ruff
- Comprehensive end-to-end testing completed

All 20 tasks from OpenSpec proposal completed successfully.

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

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

scripts/seed.py

@@ -0,0 +1,50 @@
+#!/usr/bin/env python
+"""Seed database with sample member data."""
+import asyncio
+
+from sqlalchemy import select
+
+from src.database import async_session_maker
+from src.models.member import Member
+
+
+async def seed_database():
+    """Create sample member if it doesn't exist."""
+    async with async_session_maker() as session:
+        # Check if sample member already exists
+        result = await session.execute(
+            select(Member).where(Member.email == "jane.doe@example.com")
+        )
+        existing_member = result.scalar_one_or_none()
+
+        if existing_member:
+            print("✓ Sample member already exists")
+            print(f"  ID: {existing_member.id}")
+            print(f"  Name: {existing_member.first_name} {existing_member.last_name}")
+            print(f"  Email: {existing_member.email}")
+            return
+
+        # Create sample member with minimal required data
+        # Demonstrates that only firstName is required
+        sample_member = Member(
+            first_name="Jane",
+            last_name="Doe",
+            email="jane.doe@example.com",
+            # All other fields (street, zip, city, country, phone) are None
+        )
+
+        session.add(sample_member)
+        await session.commit()
+        await session.refresh(sample_member)
+
+        print("✓ Sample member created successfully!")
+        print(f"  ID: {sample_member.id}")
+        print(f"  Name: {sample_member.first_name} {sample_member.last_name}")
+        print(f"  Email: {sample_member.email}")
+        print(f"  Created at: {sample_member.created_at}")
+
+
+if __name__ == "__main__":
+    print("Seeding database...")
+    asyncio.run(seed_database())
+    print("Done!")