[MWPW-194949] : Update route with event id

[sharmeebuilds]

After creating a new event (save draft, save, or publish), the URL is now updated from /events/new/:eventType to
/events/edit/:eventId using replace: true. This prevents duplicate event creation if the user saves again after the first
successful save.

Changes

• EventForm.tsx — capture the result from saveDraft and publishEvent in all three save handlers (handleStepSave,
  handleSaveClick, handlePublishClick); navigate to /events/edit/:eventId when result.success && result.eventId &&
  !isEditMode
• Added isEditMode and navigate to the relevant useCallback dependency arrays

Test plan

• Create a new event, click Save Draft — URL should change to /events/edit/ and the form should remain in edit mode
• Create a new event, click Publish — same redirect behaviour
• Create a new event, advance through steps triggering Save — same redirect behaviour
• Edit an existing event via /events/edit/:id — no redirect should occur on save/publish
• Verify no duplicate events are created when saving multiple times on a new form