Fix test failures and workload/websocket behavior

backend/app/models/task_dependency.py

@@ -1,5 +1,6 @@
+import uuid
 from sqlalchemy import Column, String, Integer, Enum, DateTime, ForeignKey, UniqueConstraint
-from sqlalchemy.orm import relationship
+from sqlalchemy.orm import relationship, synonym
 from sqlalchemy.sql import func
 from app.core.database import Base
 import enum
@@ -34,7 +35,7 @@ class TaskDependency(Base):
         UniqueConstraint('predecessor_id', 'successor_id', name='uq_predecessor_successor'),
     )
 
-    id = Column(String(36), primary_key=True)
+    id = Column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
     predecessor_id = Column(
         String(36),
         ForeignKey("pjctrl_tasks.id", ondelete="CASCADE"),
@@ -66,3 +67,7 @@ class TaskDependency(Base):
         foreign_keys=[successor_id],
         back_populates="predecessors"
     )
+
+    # Backward-compatible aliases for legacy field names
+    task_id = synonym("successor_id")
+    depends_on_task_id = synonym("predecessor_id")