feat(core): Improve security around logging and error monitoring

[iambriccardo]

Summary

• Harden Sentry handling for sensitive API endpoints by scrubbing request data, response/body-like context, query strings, cookies, headers, and disabling trace sampling for those routes.
• Reduce sensitive logging across ETL and destinations by avoiding passwords, row/cell values, and request/response bodies while keeping useful metadata such as table names, counts, SQL context, and phase types.
• Standardize error handling so wrapped errors use the source chain instead of embedding error strings in messages/details where possible.
• Keep etl-api database/Postgres errors from leaking through HTTP responses, while preserving internal error chains for debugging.
• Normalize observability conventions in AGENTS.md, including error = %... log fields, lowercase log prose, uppercase error messages, and table_replication_phase_type naming.

[farazdagi]

LGTM

[coveralls]

coverage: 76.397% (-0.1%) from 76.496% — make-sentry-more-secure into main

[florianschulte]

Incredible ✨