Replace jOOQ persistence with Spring Data

[azurras]

Summary

• replace handwritten jOOQ PostgreSQL adapters with Spring Data JPA for browser-session CRUD and Spring JdbcClient for native PostgreSQL semantics
• remove jOOQ code generation, generated-source coupling, CI artifact plumbing, and CodeQL database credentials
• preserve Flyway V1-V27 as the sole schema authority and keep Mongo/PostgreSQL parity contracts intact
• add validated canonical/test schema naming and SQLSTATE-only integrity redaction

Verification

• real PostgreSQL 18.4 + MongoDB test: 2,271 tests, 0 failures/errors, 75 expected opt-in skips
• clean database-free gradlew clean build: 30/30 tasks, BUILD SUCCESSFUL
• runtime classpath and production sources: zero jOOQ dependency/imports
• PostgreSQL-only candidate on port 18085: Flyway 1-27, liveness/readiness/root/representative endpoint all HTTP 200, no MongoDB connection
• V1-V27 unchanged; git diff --check clean apart from line-ending notices

Credential note

The previously visible ci-jooq-password value was only a disposable job-local container credential, never a production password. This change removes that PostgreSQL CI service and its credential entirely because jOOQ generation is gone.