refactor: update milestone/task status enums to new state machine values

Milestone: open/freeze/undergoing/completed/closed (was open/pending/deferred/progressing/closed)
Task: open/pending/undergoing/completed/closed (was open/pending/progressing/closed)

- Add MilestoneStatusEnum to schemas with typed validation
- Add started_at field to Milestone model
- Update all router/CLI references from progressing->undergoing
- Add completed status handling in task transition logic

app/models/milestone.py

@@ -6,9 +6,9 @@ import enum
 
 class MilestoneStatus(str, enum.Enum):
     OPEN = "open"
-    PENDING = "pending"
-    DEFERRED = "deferred"
-    PROGRESSING = "progressing"
+    FREEZE = "freeze"
+    UNDERGOING = "undergoing"
+    COMPLETED = "completed"
     CLOSED = "closed"
 
 class Milestone(Base):
@@ -25,6 +25,7 @@ class Milestone(Base):
     depend_on_tasks = Column(Text, nullable=True)
     project_id = Column(Integer, ForeignKey("projects.id"), nullable=False)
     created_by_id = Column(Integer, ForeignKey("users.id"), nullable=True)
+    started_at = Column(DateTime(timezone=True), nullable=True)
     created_at = Column(DateTime(timezone=True), server_default=func.now())
     updated_at = Column(DateTime(timezone=True), onupdate=func.now())
     

app/models/models.py

@@ -21,7 +21,8 @@ class TaskType(str, enum.Enum):
 class TaskStatus(str, enum.Enum):
     OPEN = "open"
     PENDING = "pending"
-    PROGRESSING = "progressing"
+    UNDERGOING = "undergoing"
+    COMPLETED = "completed"
     CLOSED = "closed"
 
 

app/models/task.py

@@ -7,7 +7,8 @@ import enum
 class TaskStatus(str, enum.Enum):
     OPEN = "open"
     PENDING = "pending"
-    PROGRESSING = "progressing"
+    UNDERGOING = "undergoing"
+    COMPLETED = "completed"
     CLOSED = "closed"
 
 class TaskPriority(str, enum.Enum):