fix(sql): apply env-backed database updates live

[wolfy-j]

Summary

• resolve SQL *_env fields during update as well as add
• swap standard SQL pools to a new DB handle on connection config updates
• keep existing borrowed DB handles alive until release, then retire them
• expand test.sh to cover env and SQL surfaces touched by fix(env,sql,cdc): prevent env name collision from corrupting SQL DSNs #367

Verification

• make lint
• ./test.sh
• go test -count=1 ./system/env/... ./service/env/... ./service/sql/... ./service/cdc/postgres/... ./api/service/sql ./api/service/cdc ./runtime/lua/modules/cdc ./boot/components/dispatchers
• go test -race -count=1 ./service/sql

Note: ./test.sh ran CDC integration compile checks only because WIPPY_CDC_IT_REPL_DSN/WIPPY_CDC_IT_ADMIN_DSN are unset.