Add PostgreSQL auto-install and auto-upgrade support

[guillaume86]

Summary

• Enable DOLI_INSTALL_AUTO=1 for PostgreSQL by removing the pgsql exclusion in docker-run.sh
• Add pgsql branches for all MySQL-specific operations: DB wait, existence check, version query, initialization, migration (backup/restore), and custom script execution
• PostgreSQL initialization reuses the existing PHP install scripts (step2.php / step5.php) which handle MySQL-to-PostgreSQL SQL conversion transparently via the pgsql driver's convertSQLFromMysql() method
• Update examples/with-pgsql/docker-compose.yml with POSTGRES_DB and DOLI_URL_ROOT
• Update README with auto-install and manual install sections for PostgreSQL, and document known limitations

PostgreSQL limitations

• DOLI_INIT_DEMO=1 is not supported with PostgreSQL (demo dump is MySQL format). A warning is logged and the setting is skipped.
• Custom .sql files in docker-init.d/ or before-starting.d/ must be written in PostgreSQL-compatible SQL (no automatic conversion).

Test plan

• Build local image and run with docker compose (PostgreSQL 15 & 16)
• Verify fresh install: 272 tables created, admin user exists, MAIN_VERSION_LAST_INSTALL set, install.lock created
• Verify web UI accessible (HTTP 200, login page renders)
• Verify container restart skips re-initialization (detects install.lock + existing DB)
• Verify MySQL regression: existing MySQL compose works unchanged (399 tables, HTTP 200)
• Verify upgrade path: version mismatch detected (22.0.4 → 23.0.0), pg_dump backup created, PHP upgrade scripts executed, DB correctly restored on failure

Note on upgrade test: The PHP migration scripts encountered SQL syntax errors from the upstream 22.0.0-23.0.0.sql migration file — this is a known upstream issue (Dolibarr/dolibarr#37425), not related to this PR. Our entrypoint code correctly detected the failure and restored the database from the pg_dump backup.

🤖 Generated with Claude Code

[guillaume86]

For your information I didn't vibe code this, I actively guided claude across steps and tried to enforce good practices ;).

[YoussefWaelMohamedLotfy]

This needs to be merged ASAP, as I am seeking to use that. Kudos for the efforts @guillaume86