feat: add Cache TTL Override per account + bump VERSION to 0.1.83

- Account-level cache TTL override: rewrite Anthropic cache_creation
  token classification (5m↔1h) in streaming/non-streaming responses
- New DB field cache_ttl_overridden in usage_log for billing tracking
- Migration 055_add_cache_ttl_overridden
- Frontend: CacheTTL override toggle in account create/edit modals
- Ent schema regenerated for new usage_log fields

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/ent/runtime/runtime.go

@@ -779,8 +779,12 @@ func init() {
 	usagelogDescImageSize := usagelogFields[28].Descriptor()
 	// usagelog.ImageSizeValidator is a validator for the "image_size" field. It is called by the builders before save.
 	usagelog.ImageSizeValidator = usagelogDescImageSize.Validators[0].(func(string) error)
+	// usagelogDescCacheTTLOverridden is the schema descriptor for cache_ttl_overridden field.
+	usagelogDescCacheTTLOverridden := usagelogFields[29].Descriptor()
+	// usagelog.DefaultCacheTTLOverridden holds the default value on creation for the cache_ttl_overridden field.
+	usagelog.DefaultCacheTTLOverridden = usagelogDescCacheTTLOverridden.Default.(bool)
 	// usagelogDescCreatedAt is the schema descriptor for created_at field.
-	usagelogDescCreatedAt := usagelogFields[29].Descriptor()
+	usagelogDescCreatedAt := usagelogFields[30].Descriptor()
 	// usagelog.DefaultCreatedAt holds the default value on creation for the created_at field.
 	usagelog.DefaultCreatedAt = usagelogDescCreatedAt.Default.(func() time.Time)
 	userMixin := schema.User{}.Mixin()