chore: rebase onto upstream v1.6.1 + bump to v1.6.1-aio.1

Rebases the aio fork onto upstream v1.6.1 (4bf867e), pulling in:
- fiat checkout + email/Nostr DM ticket notifications (PR #50)
- currency-conversion fix (v1.5.0)
- custom notification subject/body (v1.6.0)
- resend-email button on the ticket list (PR #51)

Notable merges:
- views_api.api_event_update keeps the explicit-field-list gating from
  the aio.4 security fix, with allow_fiat + fiat_currency added so an
  owner editing a fiat-enabled event keeps the fiat config.
- models.PublicEvent now exposes both upstream's fiat fields and our
  location / categories / status fields.
- migrations.py reverts to byte-identical to upstream v1.6.1 (no aio
  entries); fork schema lives in migrations_fork.py (per aiolabs/lnbits#8).
- Lint reformatted with black + ruff to match upstream style.

Contributors entry adds `padreug` (aio fork maintainer).

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

views_api.py

@@ -161,9 +161,7 @@ async def api_get_event(event_id: str) -> Event:
 
     # closing_date is filled in by create_event (defaults to end_date or
     # start_date) but the field is typed Optional, so guard for the typechecker.
-    closing_date = (
-        event.closing_date or event.event_end_date or event.event_start_date
-    )
+    closing_date = event.closing_date or event.event_end_date or event.event_start_date
     # Accept either YYYY-MM-DD or full ISO 8601 datetime (event_end_date
     # may carry a time component since v1.3.0-aio.3 / our start-end-time
     # feature).
@@ -210,10 +208,7 @@ async def api_event_create(
 
     ext_settings = await get_settings()
     user_id = wallet.wallet.user
-    is_admin = (
-        user_id == settings.super_user
-        or user_id in settings.lnbits_admin_users
-    )
+    is_admin = user_id == settings.super_user or user_id in settings.lnbits_admin_users
     if not is_admin and not ext_settings.auto_approve:
         data.status = "proposed"
 
@@ -249,9 +244,7 @@ async def api_event_update(
             status_code=HTTPStatus.NOT_FOUND, detail="Event does not exist."
         )
     if event.wallet != wallet.wallet.id:
-        raise HTTPException(
-            status_code=HTTPStatus.FORBIDDEN, detail="Not your event."
-        )
+        raise HTTPException(status_code=HTTPStatus.FORBIDDEN, detail="Not your event.")
 
     from lnbits.settings import settings
 
@@ -292,7 +285,6 @@ async def api_event_update(
 
     event.status = "approved" if (is_admin or ext_settings.auto_approve) else "proposed"
 
-
     event = await update_event(event)
 
     if event.status == "approved":