Issue #188: Terraform adoption baseline alignment

[wilhel1812]

Summary

• align Terraform staging/prod tfvars to live imported resources (zone IDs, DNS names, Access app names/policy binding)
• update backend examples to Terraform 1.5-compatible S3 backend args for R2
• add D1 read replication mode modeling to prevent import drift
• keep Access application in adoption-safe mode with ignore_changes = all
• fix local tf:validate/init --backend=false reliability by using temporary TF_DATA_DIR

Why

After live import into state, baseline plan revealed drift from placeholder/default assumptions. This PR codifies the known-good baseline so import-first rollout remains zero-diff and safe.

Verification

• npm run tf:fmt
• npm run tf:validate
• npm test
• npm run build