feat(database): Implement Automated Slow Query Logging and Weekly Digest Report

[Dydex]

Rationale & Scope

Surface database performance regressions proactively by logging queries exceeding a duration threshold and rolling them up into a weekly digest for the team, instead of relying on ad-hoc complaints.

Concrete Tasks

• Enable Postgres slow query logging above a configurable duration threshold.
• Build a scheduled job aggregating the past week's slow queries by frequency and average duration.
• Deliver the digest report via email/Slack with the top offending query patterns.

Acceptance Criteria

• Queries exceeding the threshold are consistently captured in the slow query log.
• The weekly digest accurately ranks the top slow query patterns by frequency and duration.

Suggested Branch Name

git checkout -b feat/database-slow-query-digest