chore(activities): reroute CreateActivityDialog through TicketApiService.createEvent

The aiolabs/events extension on its signer-abstraction branch (commit
66076d6) constructs and publishes kind-31922 NIP-52 calendar events
server-side via NostrSigner — POST /events/api/v1/events accepts a
CreateEventRequest payload, signs through the operator's signer, and
broadcasts to configured relays. The webapp no longer needs to sign
calendar events client-side.

Changes:
- ActivitiesNostrService.ts: delete publishCalendarEvent() and its
  helper imports (finalizeEvent, EventTemplate, buildCalendarTimeEventTags,
  the local hexToUint8Array). The subscribe / query paths stay — the
  service still reads NIP-52 events off relays for the activity feed.
  Docstring updated to reflect the read-only role and point at the
  events extension for the publish path.
- CreateActivityDialog.vue: swap the publish flow.
  - Drop ActivitiesNostrService injection + currentUser.value.prvkey read.
  - Inject TicketApiService instead; pull invoiceKey from
    currentUser.value.wallets[0].inkey (same pattern as EventsPage.vue
    handleCreateEvent).
  - Build CreateEventRequest with amount_tickets: 0, price_per_ticket: 0
    (events extension treats 0 as unlimited/not-ticketed per
    models.py:45-46 per lnbits 22:30Z audit).
  - Fold summary + description into the events extension's `info`
    field since CreateEventRequest has no separate summary slot.
  - Update toast on success to "Activity created!" (server publishes
    to relays via the signer, not the webapp).

Approval-workflow caveat documented inline in the submit handler:
non-admin users on instances with auto_approve=false (the default)
land in the proposal queue and don't publish to relays until an admin
approves. Admins / auto_approve=true instances publish immediately.
This is the intended new behavior — operators can flip auto_approve
on the events extension config per-instance if they want the legacy
direct-publish moderation posture.

This is webapp's second bucket-A leg per aiolabs/lnbits#9 phase-1.
The remaining `currentUser.value.prvkey` reads stay until the
atomic User.prvkey field-removal PR (Q1.2 Option (b)).

Refs:
- log:2026-05-28T22:30Z (lnbits Q2.1 audit verifying ticket-less
  acceptance + approval-workflow caveat)
- ~/dev/coordination/webapp-design-questions.md Q2.1
- aiolabs/events signer-abstraction commit 66076d6 (the server-side
  publish path)
- aiolabs/lnbits cascade tip 861f427c deployed to aio-demo

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/lib/api/lnbits.ts

@@ -112,12 +112,29 @@ export class LnbitsAPI extends BaseService {
 
     if (!response.ok) {
       const errorText = await response.text()
+      // Try to surface FastAPI's `{"detail": "..."}` shape; fall back to raw
+      // body for non-JSON errors. Without this, every backend error renders
+      // as a generic "API request failed: <status>" and you can't distinguish
+      // "wrong endpoint" from "expired token" from "validation failure".
+      let detail: string = errorText
+      try {
+        const parsed = JSON.parse(errorText)
+        if (parsed && typeof parsed.detail === 'string') {
+          detail = parsed.detail
+        } else if (parsed && Array.isArray(parsed.detail)) {
+          // pydantic ValidationError: take the first msg
+          detail = parsed.detail[0]?.msg ?? errorText
+        }
+      } catch {
+        // body wasn't JSON; keep the raw text in `detail`
+      }
       console.error('LNBits API Error:', {
+        endpoint,
         status: response.status,
         statusText: response.statusText,
-        errorText
+        detail,
       })
-      throw new Error(`API request failed: ${response.status} ${response.statusText}`)
+      throw new Error(`LNbits ${endpoint} ${response.status}: ${detail || response.statusText}`)
     }
 
     const data = await response.json()
@@ -186,8 +203,12 @@ export class LnbitsAPI extends BaseService {
   }
 
   async updateProfile(data: Partial<User>): Promise<User> {
-    return this.request<User>('/auth/update', {
+    // aiolabs/lnbits PR #26 (gap-fill 869f67c3) wired
-      method: 'PUT',
+    // _publish_nostr_metadata_event into PATCH /api/v1/auth
+    // (auth_api.py:546). The legacy PUT /auth/update route does not
+    // exist on the post-cascade server.
+    return this.request<User>('/auth', {
+      method: 'PATCH',
       body: JSON.stringify(data),
     })
   }