Show team-based access in project access management

- Add source, team_slug, team_role fields to AccessPermissionResponse schema
- Update list_project_permissions endpoint to include team members with source="team"
- Display team-based access in AccessManagement component with read-only styling
- Add "Source" column to differentiate explicit vs team-based permissions
- Team-based access shows "Via team" in actions column (not editable)

backend/app/schemas.py

@@ -911,6 +911,9 @@ class AccessPermissionResponse(BaseModel):
     level: str
     created_at: datetime
     expires_at: Optional[datetime]
+    source: Optional[str] = "explicit"  # "explicit" or "team"
+    team_slug: Optional[str] = None  # Team slug if source is "team"
+    team_role: Optional[str] = None  # Team role if source is "team"
 
     class Config:
         from_attributes = True