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/usagelog/where.go

@@ -200,6 +200,11 @@ func ImageSize(v string) predicate.UsageLog {
 	return predicate.UsageLog(sql.FieldEQ(FieldImageSize, v))
 }
 
+// CacheTTLOverridden applies equality check predicate on the "cache_ttl_overridden" field. It's identical to CacheTTLOverriddenEQ.
+func CacheTTLOverridden(v bool) predicate.UsageLog {
+	return predicate.UsageLog(sql.FieldEQ(FieldCacheTTLOverridden, v))
+}
+
 // CreatedAt applies equality check predicate on the "created_at" field. It's identical to CreatedAtEQ.
 func CreatedAt(v time.Time) predicate.UsageLog {
 	return predicate.UsageLog(sql.FieldEQ(FieldCreatedAt, v))
@@ -1440,6 +1445,16 @@ func ImageSizeContainsFold(v string) predicate.UsageLog {
 	return predicate.UsageLog(sql.FieldContainsFold(FieldImageSize, v))
 }
 
+// CacheTTLOverriddenEQ applies the EQ predicate on the "cache_ttl_overridden" field.
+func CacheTTLOverriddenEQ(v bool) predicate.UsageLog {
+	return predicate.UsageLog(sql.FieldEQ(FieldCacheTTLOverridden, v))
+}
+
+// CacheTTLOverriddenNEQ applies the NEQ predicate on the "cache_ttl_overridden" field.
+func CacheTTLOverriddenNEQ(v bool) predicate.UsageLog {
+	return predicate.UsageLog(sql.FieldNEQ(FieldCacheTTLOverridden, v))
+}
+
 // CreatedAtEQ applies the EQ predicate on the "created_at" field.
 func CreatedAtEQ(v time.Time) predicate.UsageLog {
 	return predicate.UsageLog(sql.FieldEQ(FieldCreatedAt, v))