fix(audit): stop duplicate and empty audit rows

- Set env var version and compose parsing version while creating, so a create writes one row
- Record no rows for the auto-created preview copy of an env var
- Record env and application API updates only with the fields that really changed
- Store no change data for new env vars, and null for empty change data
- Store metadata team_id as an integer
- Drop the unused level and resource indexes of audit_events

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

app/Models/AuditEvent.php

@@ -123,7 +123,7 @@ class AuditEvent extends Model
      */
     public static function recordModelMutation(string $event, array $context, array $changes): void
     {
-        self::recordWithChanges($event, $context, $changes);
+        self::recordWithChanges($event, $context, $changes ?: null);
     }
 
     /**
@@ -161,6 +161,11 @@ class AuditEvent extends Model
      */
     private static function attributesFor(string $event, array $context, ?array $changes, string $level): array
     {
+        // API tokens store team_id as a string. Keep it an integer, so JSON filters on metadata work.
+        if (is_string($context['team_id'] ?? null) && ctype_digit($context['team_id'])) {
+            $context['team_id'] = (int) $context['team_id'];
+        }
+
         $teamId = data_get(auth()->user()?->currentAccessToken(), 'team_id')
             ?? (array_key_exists('team_id', $context)
                 ? $context['team_id']