Add cross-driver testsuite for MySQL and Postgres

[alganet]

Refactor DbTest and MapperTest onto a shared DatabaseTestCase so the existing tests run against SQLite, MySQL, and Postgres. The driver, DSN, and credentials are selected from environment variables; default to in-memory SQLite to preserve the current zero-config experience. A docker-compose.yml provides MySQL and Postgres locally on non-default ports, and CI fans out into a three-driver matrix using GitHub Actions services.

Fix Mapper::checkNewIdentity to wrap lastInsertId() in a savepoint on Postgres. After an INSERT with an explicit id, Postgres errors with "lastval is not yet defined in this session" and marks the surrounding transaction as aborted; the catch swallowed the exception but the subsequent commit then discarded the row. The savepoint contains the abort. MySQL is excluded because issuing SAVEPOINT between the INSERT and LAST_INSERT_ID() resets the latter to 0.

Also fix four raw-SQL portability bugs in MapperTest that SQLite and MySQL had hidden: double-quoted string literals (Postgres reads them as identifiers) and a VARCHAR/integer comparison.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.72%. Comparing base (a3c9be3) to head (3855e48).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##             master     #119   +/-   ##
=========================================
  Coverage     99.71%   99.72%           
- Complexity      145      149    +4     
=========================================
  Files             3        3           
  Lines           353      362    +9     
=========================================
+ Hits            352      361    +9     
  Misses            1        1           

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[Copilot]

Pull request overview

This PR refactors the test harness so the existing DB/Mapper integration tests can run against multiple PDO backends (SQLite/MySQL/Postgres) selected via environment variables, and it adjusts Mapper::checkNewIdentity() to avoid Postgres transaction aborts when lastInsertId() is undefined.

Changes:

• Introduce a shared DatabaseTestCase + ConnectionFactory to run tests across SQLite/MySQL/Postgres (defaulting to in-memory SQLite).
• Add driver-aware DDL helpers (Schema::pkAuto(), Schema::dateTime()) and fix raw SQL portability issues in tests.
• Wrap Postgres lastInsertId() inside a savepoint to contain transaction aborts, with targeted tests for the behavior.

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
tests/MapperTest.php	Migrates to shared DB test case, uses driver-aware schema, adds savepoint behavior tests, and fixes SQL portability issues.
tests/DbTest.php	Migrates to shared DB test case and makes one SQLite-specific assertion explicitly skipped on other drivers.
tests/Database/Schema.php	Adds driver-specific DDL fragments for auto PK and datetime types.
tests/Database/DriverUnavailable.php	Adds a typed exception for missing PDO drivers to cleanly skip tests.
tests/Database/DatabaseTestCase.php	Adds shared connection setup, table reset helper, and Postgres sequence resync helper.
tests/Database/ConnectionFactory.php	Adds env-driven PDO connection creation with default DSNs for local docker ports.
src/Mapper.php	Adds savepoint wrapping around Postgres lastInsertId() to prevent transaction abort from discarding inserts.
phpunit.xml.dist	Splits tests into unit vs database testsuites by explicit file list.
docker-compose.yml	Adds local MySQL/Postgres services on non-default host ports with healthchecks.
composer.json	Adds convenience scripts to run PHPUnit against sqlite/mysql/pgsql (and all in sequence).
CONTRIBUTING.md	Documents how to run the multi-driver tests locally with docker compose and composer scripts.
.github/workflows/ci.yml	Fans CI tests out into separate sqlite/mysql/pgsql jobs using GitHub Actions services.
.env.example	Documents supported DB environment variables for the integration tests.

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