Add bounded database response size diagnostics (#17504)

Count database response value sizes by public caller and static table for one explicit UTC window of at most 60 seconds. Keep diagnostics off by default and exclude SQL, parameters, returned values, errors, and credentials from output. Preserve lazy execution, transaction boundaries, and no-replay behavior.

Verification: full build and recursive typecheck; 63 focused database and PostgreSQL tests; eight physical disconnect tests with capture enabled.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

doc/DATABASE.md

@@ -320,6 +320,31 @@ DATABASE_MAX_LIFETIME_SECONDS=1800   # recycle a pooled connection after this lo
 DATABASE_APPLICATION_NAME=paperclip  # application_name in pg_stat_activity; default: paperclip
 ```
 
+### Bounded response diagnostics
+
+`PAPERCLIP_DB_RESPONSE_CAPTURE_WINDOW=<start>/<end>` enables one explicit UTC
+window. Both timestamps use ISO format ending in `Z`. The window lasts at most
+60 seconds and starts within 30 minutes. Unset, invalid, and expired windows
+leave database construction unchanged. An expired window stays inactive after a
+restart; remove the setting after the investigation.
+
+The diagnostic measures awaited Postgres.js `unsafe` responses before Drizzle
+column decoding. It retains the Drizzle builder caller for normal, prepared,
+transaction, and dedicated-pool execution. It issues no queries.
+It logs the public server caller locations, static schema table, operation,
+query/row counts, and response value sizes. It emits at most 128 aggregate
+groups and a summary at the deadline. It never logs SQL, parameters, result
+values, connection strings, or query errors. In-flight queries continue normally.
+
+Look for `paperclip.db_response_capture.entry.v1` and
+`paperclip.db_response_capture.summary.v1` in the process logs. Tagged raw-driver calls, streams, unawaited raw-driver
+dispatch, and protocol overhead are not measured. Relational queries use a driver-level caller fallback.
+Queries still in flight at the deadline are reported separately. Sizes describe
+driver values before column decoding, not billed network bytes. Complex parsed
+values use JSON size estimates, counted in `estimatedValues`. Reconcile them with
+provider metering and socket measurements. Serialization adds temporary CPU and memory work;
+measure the final transfer rate after the window expires.
+
 ### Push the schema
 
 ```sh