Migrate JPA persistence to PostgreSQL

[heisenbugged]

Summary

• Replace SQLite runtime wiring with PostgreSQL, Flyway Community migrations, and Hibernate schema validation.
• Add a PostgreSQL production service plus deployment workflow exports for the database password and data directory.
• Add the baseline PostgreSQL schema, migration notes, and a pgloader transform for SQLite epoch-millisecond timestamps.

Test Plan

• docker build -t ti4-postgres-flyway-check .
• docker compose -f docker-compose.production.yml config --quiet with required environment variables set
• Started postgres:18.3-alpine, booted the app image against an empty database, and verified Flyway applied V1 before Hibernate initialized
• Ran pgloader from local storage/tibot.db into PostgreSQL using scripts/pgloader-ti4-transforms.lisp, then booted the app image against the imported database and verified Flyway baselined plus Hibernate initialized

Notes

• Local host Maven compile was not usable because the installed JDK is 21 and this repo compiles with Java 26; Docker build uses the repo-declared Java 26 toolchain.

[github-actions]

🔬 Test Results

✅ JSON Validation

No JSON files changed.

---

✅ Formatting Checks Passed

All files pass Spotless formatting.

---

✅ JUnit Tests Passed

All tests passed successfully.