ci: standardize the Continuous Integration workflow

[guillaume-sainthillier]

Part of normalizing CI across SILARHI projects. The standard:

File / name	.github/workflows/continuous-integration.yml, name: 'Continuous Integration'
Triggers	pull_request + push to the default branch (*.x + main for libraries); no refs/pull/*
PHP jobs	matrix "Generate job matrix", qa "QA Checks" (Laminas)
Front-end jobs	lint "Lint", test "Test", build "Build" (only those the project has)
Gate	ci-passed "CI passed", which needs every job; the only check required by the branch rules
Steps	Checkout, Setup PHP, Install Composer dependencies, Setup Node.js, Install dependencies, then Biome / Prettier / Typecheck / Knip / Test / Build
Other workflows	Title Case names, every job named with the same names across projects ("Ensure base image", "Build and push image", "Deploy to production"…)

Commits

• ci: standardize the Continuous Integration workflow: Same layout in every SILARHI project: one continuous-integration.yml named "Continuous Integration", with the Lint and Build jobs and CI passed, which aggregates them all and is the only check required by the branch rules. It replaces ci.yml (Hadolint becomes the Lint job, the image matrix the Build job); the README badge points to the new workflow file.