fix(jira): show test Jira tickets on technique page (correct entity model)

Techniques don't have their own Jira tickets — tickets exist on tests
and campaigns. The previous JiraLinkPanel entityType='technique' always
returned empty.

Backend: add entity_ids (list) filter to GET /jira/links so multiple
  test IDs can be fetched in a single request.
Frontend API: listJiraLinks() accepts entity_ids[] and serialises them
  as repeated query params (required by FastAPI List[UUID] parsing).
TechniqueDetailPage: replace JiraLinkPanel with TechniqueJiraSection —
  a dedicated read-only component that:
  - Takes technique.tests (already loaded)
  - Batch-fetches all test Jira links in one request
  - Shows test name + ticket key + status + priority + open-in-Jira link
  - Hides itself when no tickets exist (avoids empty panel)

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

backend/app/routers/jira.py

@@ -72,14 +72,16 @@ def create_link(
 def list_links(
     entity_type: Optional[JiraLinkEntityType] = None,
     entity_id: Optional[UUID] = None,
+    entity_ids: Optional[list[UUID]] = Query(default=None, description="Filter by multiple entity IDs"),
     db: Session = Depends(get_db),
     user: User = Depends(get_current_user),
 ):
-    """List Jira links, optionally filtered by entity."""
+    """List Jira links, optionally filtered by entity or a list of entity IDs."""
     return jira_service.list_links(
         db,
         entity_type=entity_type,
         entity_id=entity_id,
+        entity_ids=entity_ids,
     )