chore(terraform): preserve live Cloud SQL binlog flag

[jjcc123312]

Problem / evidence

A refreshing production Terraform plan proposed removing the live Cloud SQL flag log_bin_trust_function_creators=on. gcloud sql instances describe newapi-mysql confirms the flag is active alongside the declared database settings, and the instance is RUNNABLE with a 216 GB disk and the expected tier.

Scope / design

Declare the existing flag in the Cloud SQL module so Terraform preserves current production behavior instead of removing it during an unrelated apply.

Impact / risks

This is desired-state alignment only: production already has the exact value. No database restart, failover, replacement, or immediate infrastructure apply is required. Removing this flag could break function/trigger creation under binary logging, so preserving it is the conservative choice.

Validation

• terraform fmt
• terraform validate
• Fresh local production plan no longer contains a Cloud SQL update
• Plan remains 0 destroy, with no Cloud SQL or secret replacement

Deployment recommendation

• Router deploy: not required
• Other deploy targets: Terraform desired state only; no production apply needed for this PR
• Risk / validation: retain the live flag and verify future full plans remain free of Cloud SQL changes