feat(campaigns): campaign start date — scheduled activation, Jira start_date

DB: migration b047 adds start_date (DateTime nullable) + index to campaigns.

Backend:
- Campaign model: start_date field
- CampaignCreate/Update schemas: accept start_date (ISO string)
- CRUD service: persist + serialize start_date in both serializers
- Activation endpoint: blocks manual activation if start_date is in the future
  (campaign will auto-activate via scheduler)
- Scheduler: new hourly job _run_scheduled_campaign_activation — finds draft
  campaigns with start_date <= now, activates them, creates Jira tickets,
  notifies red_tech team
- Jira: campaign + test tickets now include JIRA_START_DATE_FIELD (configurable,
  default customfield_10015). Campaign uses start_date if set, else created_at.
  Tests inherit campaign start_date.
- config.py: JIRA_START_DATE_FIELD setting

Frontend:
- Campaign type: start_date field on Campaign + CampaignSummary
- CampaignCreatePayload: start_date optional field
- Create form: date picker with min=today, warning message explaining behavior
- Campaign detail header: start_date badge showing days remaining or started date

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/services/campaign_crud_service.py

@@ -72,6 +72,7 @@ def serialize_campaign(db: Session, campaign: Campaign) -> dict:
         "threat_actor_id": str(campaign.threat_actor_id) if campaign.threat_actor_id else None,
         "threat_actor_name": actor.name if actor else None,
         "created_by": str(campaign.created_by) if campaign.created_by else None,
+        "start_date": campaign.start_date.isoformat() if campaign.start_date else None,
         "scheduled_at": campaign.scheduled_at.isoformat() if campaign.scheduled_at else None,
         "completed_at": campaign.completed_at.isoformat() if campaign.completed_at else None,
         "target_platform": campaign.target_platform,
@@ -100,6 +101,7 @@ def serialize_campaign_summary(db: Session, campaign: Campaign) -> dict:
         "status": campaign.status,
         "threat_actor_id": str(campaign.threat_actor_id) if campaign.threat_actor_id else None,
         "threat_actor_name": actor.name if actor else None,
+        "start_date": campaign.start_date.isoformat() if campaign.start_date else None,
         "target_platform": campaign.target_platform,
         "tags": campaign.tags or [],
         "created_at": campaign.created_at.isoformat() if campaign.created_at else None,
@@ -160,6 +162,7 @@ def create_campaign(
     target_platform: Optional[str] = None,
     tags: Optional[list[str]] = None,
     scheduled_at: Optional[str] = None,
+    start_date: Optional[str] = None,
 ) -> dict:
     """Create a new campaign. Does not commit; caller commits."""
     campaign = Campaign(
@@ -171,6 +174,7 @@ def create_campaign(
         tags=tags or [],
         created_by=creator_id,
         scheduled_at=datetime.fromisoformat(scheduled_at) if scheduled_at else None,
+        start_date=datetime.fromisoformat(start_date) if start_date else None,
     )
     db.add(campaign)
     db.flush()
@@ -213,6 +217,8 @@ def update_campaign(
 
     if "scheduled_at" in fields and fields["scheduled_at"]:
         fields["scheduled_at"] = datetime.fromisoformat(fields["scheduled_at"])
+    if "start_date" in fields and fields["start_date"]:
+        fields["start_date"] = datetime.fromisoformat(fields["start_date"])
 
     for field, value in fields.items():
         setattr(campaign, field, value)