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>

config.json

@@ -1,8 +1,8 @@
 {
   "id": "events",
-  "version": "1.6.1",
+  "version": "1.6.1-aio.1",
   "name": "Events",
-  "repo": "https://github.com/lnbits/events",
+  "repo": "https://git.atitlan.io/aiolabs/events",
   "short_description": "Sell and register event tickets",
   "description": "",
   "tile": "/events/static/image/events.png",
@@ -32,6 +32,11 @@
       "name": "motorina0",
       "uri": "https://github.com/motorina0",
       "role": "Developer"
+    },
+    {
+      "name": "padreug",
+      "uri": "https://git.atitlan.io/padreug",
+      "role": "Developer (aio fork: approval workflow + NIP-52 Nostr sync + edit gating)"
     }
   ],
   "images": [