feat(db): add MySQL 8.4 support (#4048)

Add MySQL 8.4 compatibility, including a utf8mb4 conversion migration,
hardened foreign key handling, and expanded CI database coverage.

Migrations:
- Add Mysql84Utf8mb4Conversion migration using
  sqlscripts/3.4.3_mysql84_utf8mb4_conversion.sql via executeScript()
- Drop ospos_people composite index before conversion, since its
  prefix length exceeds the 3072-byte key limit under utf8mb4
- Add assertNoCollationCollisions() pre-flight check to fail fast on
  unique values that collide under utf8mb4_unicode_520_ci, instead of
  hitting "Duplicate entry" partway through ALTER TABLE
- Wrap the conversion in try/catch so foreign keys are recreated on
  failure; log restore errors separately so they don't mask the
  original exception
- Throw RuntimeException if re-adding the people index fails
- Remove the re-add of the sales_items_taxes FK in down(), which
  MySQL 8.4 rejects without a unique key
- Revert edits to historical migrations; fix FK handling and table
  names

migration_helper:
- Add shared dropAllForeignKeyConstraints() and
  recreateForeignKeyConstraints(); table/column now optional, dropping
  all FKs in the schema when omitted
- Match CONSTRAINT_SCHEMA when joining KEY_COLUMN_USAGE to
  REFERENTIAL_CONSTRAINTS to avoid cross-schema name collisions
- Rebuild FK lookup with the query builder and bound values instead
  of interpolated SQL

CI/tests:
- Add mysql:5.7, mariadb:10.6 and mariadb:10.11 to PHPUnit matrix
- Use master instead of latest image tag; improve CI robustness
- Mock table() in FailedQueryConnectionTrait so query builder chains
  work against the failing connection

Signed-off-by: objecttothis <17935339+objecttothis@users.noreply.github.com>
Co-authored-by: aliworksx08 <57456290+aliworksx08@users.noreply.github.com>
Co-authored-by: jekkos <jeroen.peelaerts@gmail.com>
Co-authored-by: objecttothis <17935339+objecttothis@users.noreply.github.com>
Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>

.github/workflows/phpunit.yml

@@ -27,7 +27,7 @@ permissions:
 
 jobs:
   test:
-    name: PHP ${{ matrix.php-version }} Tests
+    name: PHP ${{ matrix.php-version }} / ${{ matrix.db-image }} Tests
     runs-on: ubuntu-22.04
 
     strategy:
@@ -37,6 +37,13 @@ jobs:
           - '8.2'
           - '8.3'
           - '8.4'
+        db-image:
+          - 'mariadb:10.5'
+          - 'mariadb:10.6'
+          - 'mariadb:10.11'
+          - 'mysql:5.7'
+          - 'mysql:8.0'
+          - 'mysql:8.4'
 
     steps:
       - name: Checkout
@@ -68,7 +75,7 @@ jobs:
       - name: Install npm dependencies
         run: npm install
 
-      - name: Start MariaDB
+      - name: Start database
         run: |
           docker run -d --name mysql \
              -e MYSQL_ROOT_PASSWORD=root \
@@ -76,13 +83,19 @@ jobs:
             -e MYSQL_USER=admin \
             -e MYSQL_PASSWORD=pointofsale \
             -p 3306:3306 \
-            mariadb:10.5
-          # Wait for MariaDB to be ready
+            ${{ matrix.db-image }}
+          # Wait for database to be ready (max 60 attempts)
+          retries=0
           until docker exec mysql mysqladmin ping -h 127.0.0.1 -u root -proot --silent; do
-            echo "Waiting for MariaDB..."
+            retries=$((retries + 1))
+            if [ $retries -ge 60 ]; then
+              echo "Database failed to start after 60 attempts"
+              exit 1
+            fi
+            echo "Waiting for database... (attempt $retries/60)"
             sleep 2
           done
-          echo "MariaDB is ready!"
+          echo "Database is ready!"
 
           # Grant admin the CREATE/DROP privileges it needs to drop and
           # recreate the test database at the start of each test class.
@@ -140,14 +153,18 @@ jobs:
           MYSQL_HOST_NAME: 127.0.0.1
         run: composer test -- --no-coverage --log-junit test-results/junit.xml
 
+      - name: Set artifact name
+        if: always()
+        run: echo "DB_LABEL=$(echo '${{ matrix.db-image }}' | tr ':' '-')" >> $GITHUB_ENV
+
       - name: Upload test results
         uses: actions/upload-artifact@v4
         if: always()
         with:
-          name: test-results-php-${{ matrix.php-version }}
+          name: test-results-php-${{ matrix.php-version }}-${{ env.DB_LABEL }}
           path: test-results/
           retention-days: 30
 
-      - name: Stop MariaDB
+      - name: Stop database
         if: always()
         run: docker stop mysql && docker rm mysql