Upgrade envio to 3.0.0-alpha.23

Migrate handlers from per-contract Contract.Event.handler() API to the
unified indexer.onEvent() API, and add storage backend selection block
in config.yaml (clickhouse commented out, postgres enabled).

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

Author: moose-code

config.yaml

@@ -2,6 +2,10 @@
 name: polymarket-v2-indexer
 description: Polymarket V2 — CTF Exchange, PolyUSD, Rewards
 
+storage:
+  postgres: true
+  # clickhouse: true  # enable to additionally sync indexed data to ClickHouse
+
 field_selection:
   transaction_fields:
     - hash

package.json

@@ -14,7 +14,7 @@
     "vitest": "4.0.18"
   },
   "dependencies": {
-    "envio": "3.0.0-alpha.21"
+    "envio": "3.0.0-alpha.23"
   },
   "optionalDependencies": {
     "generated": "./polymarket-v2-indexer/../generated"