feat(templates,campaigns): validate MITRE technique IDs, surface template suggestions first, manager can re-approve rejected campaigns

- TestTemplate/TemplateSuggestion creation and updates now reject any
  mitre_technique_id that doesn't match a real, already-synced MITRE
  ATT&CK technique. Frontend swaps the free-text ID input for a
  technique picker.
- Test Catalog now shows pending template suggestions before the
  catalog grid, with full field detail (platform, severity, tool,
  atomic ID, source URL, remediation) instead of just name/procedure.
- A manager can edit and directly re-approve a campaign they previously
  rejected, instead of needing the original lead to resubmit it.

backend/app/services/test_template_service.py

@@ -12,7 +12,7 @@ from sqlalchemy import func, or_
 from sqlalchemy.orm import Session
 
 # Import EntityNotFoundError from app.domain.errors
-from app.domain.errors import EntityNotFoundError
+from app.domain.errors import BusinessRuleViolation, EntityNotFoundError
 
 # Import TestTemplate from app.models.test_template
 from app.models.test_template import TestTemplate
@@ -235,9 +235,22 @@ def get_template_or_raise(db: Session, template_id: uuid.UUID) -> TestTemplate:
     return template
 
 
+def validate_mitre_technique_id(db: Session, mitre_technique_id: str) -> None:
+    """Raise BusinessRuleViolation unless *mitre_technique_id* matches a real,
+    already-synced MITRE ATT&CK technique — free text like "made up" or a
+    typo'd ID would otherwise silently create an orphaned template that can
+    never be found via technique lookups or coverage reporting."""
+    exists = db.query(Technique).filter(Technique.mitre_id == mitre_technique_id).first()
+    if not exists:
+        raise BusinessRuleViolation(
+            f"'{mitre_technique_id}' is not a known MITRE ATT&CK technique ID"
+        )
+
+
 # Define function create_template
 def create_template(db: Session, **fields: object) -> TestTemplate:
     """Create a test template from keyword args (e.g. payload.model_dump()). Does NOT commit."""
+    validate_mitre_technique_id(db, fields["mitre_technique_id"])
     # Assign template = TestTemplate(**fields)
     template = TestTemplate(**fields)
     # Stage new record(s) for database insertion
@@ -249,6 +262,8 @@ def create_template(db: Session, **fields: object) -> TestTemplate:
 # Define function update_template
 def update_template(db: Session, template_id: uuid.UUID, **fields: object) -> TestTemplate:
     """Update an existing template. Raises EntityNotFoundError if not found. Does NOT commit."""
+    if fields.get("mitre_technique_id"):
+        validate_mitre_technique_id(db, fields["mitre_technique_id"])
     # Assign template = get_template_or_raise(db, template_id)
     template = get_template_or_raise(db, template_id)
     # Iterate over fields.items()