feat(jira+tests): 5 improvements from review

1. Jira status → In Progress on Start Execution
   - push_test_event calls set_issue_status("In Progress") when
     new_state == "red_executing" (non-fatal, separate try/except)

2. Jira assignee set on Start Execution
   - assign_issue() called with actor.jira_account_id when operator
     clicks Start (non-fatal)

3. Standalone tests parent ticket (OFS-20798)
   - New jira.parent_ticket_standalone config key
   - get_jira_parent_ticket_standalone() falls back to parent_ticket
   - auto_create_test_issue uses standalone parent for non-campaign tests
   - Exposed in /system/jira-config GET+PATCH and SettingsPage UI

4. Tests table: Created + Updated columns
   - Add Created column (created_at), fix Updated to show updated_at
   - Both use UTC-aware date parsing (append Z if no tz suffix)
   - updated_at added to Test TypeScript interface

5. Sortable columns in tests table
   - All 7 columns sortable: Name, Technique, State, Current Team,
     Platform, Created, Updated
   - Click to sort asc, click again to reverse; ChevronUp/Down indicator
   - Default sort: Created desc (newest first)

frontend/src/types/models.ts

@@ -70,6 +70,7 @@ export interface Test {
   result: TestResult | null;
   state: TestState;
   created_at: string;
+  updated_at: string | null;
 
   // Red Team fields
   red_summary: string | null;