Add project creation from team dashboard and update seed data

- Add project creation modal to TeamDashboardPage with team_id assignment
- Update createProject API function to accept optional team_id
- Update seed data to create a "Demo Team" and assign all projects to it
- Admin user is added as team owner when present

backend/app/seed.py

@@ -5,7 +5,7 @@ import hashlib
 import logging
 from sqlalchemy.orm import Session
 
-from .models import Project, Package, Artifact, Tag, Upload, PackageVersion, ArtifactDependency
+from .models import Project, Package, Artifact, Tag, Upload, PackageVersion, ArtifactDependency, Team, TeamMembership, User
 from .storage import get_storage
 
 logger = logging.getLogger(__name__)
@@ -149,6 +149,33 @@ def seed_database(db: Session) -> None:
     logger.info("Seeding database with test data...")
     storage = get_storage()
 
+    # Find or use admin user for team ownership
+    admin_user = db.query(User).filter(User.username == "admin").first()
+    team_owner_username = admin_user.username if admin_user else "seed-user"
+
+    # Create a demo team
+    demo_team = Team(
+        name="Demo Team",
+        slug="demo-team",
+        description="A demonstration team with sample projects",
+        created_by=team_owner_username,
+    )
+    db.add(demo_team)
+    db.flush()
+
+    # Add admin user as team owner if they exist
+    if admin_user:
+        membership = TeamMembership(
+            team_id=demo_team.id,
+            user_id=admin_user.id,
+            role="owner",
+            invited_by=team_owner_username,
+        )
+        db.add(membership)
+        db.flush()
+
+    logger.info(f"Created team: {demo_team.name} ({demo_team.slug})")
+
     # Create projects and packages
     project_map = {}
     package_map = {}
@@ -158,7 +185,8 @@ def seed_database(db: Session) -> None:
             name=project_data["name"],
             description=project_data["description"],
             is_public=project_data["is_public"],
-            created_by="seed-user",
+            created_by=team_owner_username,
+            team_id=demo_team.id,  # Assign to demo team
         )
         db.add(project)
         db.flush()  # Get the ID
@@ -174,7 +202,7 @@ def seed_database(db: Session) -> None:
             db.flush()
             package_map[(project_data["name"], package_data["name"])] = package
 
-    logger.info(f"Created {len(project_map)} projects and {len(package_map)} packages")
+    logger.info(f"Created {len(project_map)} projects and {len(package_map)} packages (assigned to {demo_team.slug})")
 
     # Create artifacts, tags, and versions
     artifact_count = 0
@@ -212,7 +240,7 @@ def seed_database(db: Session) -> None:
             size=size,
             content_type=artifact_data["content_type"],
             original_name=artifact_data["filename"],
-            created_by="seed-user",
+            created_by=team_owner_username,
             s3_key=s3_key,
             ref_count=ref_count,
         )
@@ -235,7 +263,7 @@ def seed_database(db: Session) -> None:
                 artifact_id=sha256_hash,
                 version=artifact_data["version"],
                 version_source="explicit",
-                created_by="seed-user",
+                created_by=team_owner_username,
             )
             db.add(version)
             version_count += 1
@@ -246,7 +274,7 @@ def seed_database(db: Session) -> None:
                 package_id=package.id,
                 name=tag_name,
                 artifact_id=sha256_hash,
-                created_by="seed-user",
+                created_by=team_owner_username,
             )
             db.add(tag)
             tag_count += 1