Add CI, a pre-commit hook, and an accessibility pass on the panel's own views

CI (.github/workflows/tests.yml) reuses docker-compose.test.yml verbatim for
the Postgres job rather than re-describing that environment in YAML, so the
Docker image stays the single source of truth for it.

Fixes a real mismatch found while wiring PHP versions into the workflow:
composer.json declared "php": "^8.3", but the locked Symfony packages require
>=8.4.1 — installing on 8.3 would fail at `composer install`, exactly what
the Dockerfile's own comment already warned about. Bumped the constraint and
resynced composer.lock's content-hash (no package versions changed).

The pre-commit hook (.githooks/pre-commit, activated via
`git config core.hooksPath` in post-autoload-dump) runs `pint --dirty --test`
and refuses to commit unformatted files rather than silently rewriting them.

The accessibility pass only touches this app's own hand-written Blade views,
not Filament's components: aria-hidden on icons that repeat adjacent text,
an aria-label on the one icon that is the only signal of a health check's
severity, rel="noopener" and a labelled announcement on preview links that
open in a new tab.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

lang/es/panel.php

@@ -196,6 +196,8 @@ return [
         'heading' => 'Enlaces de vista previa',
         'hint' => 'Se pueden compartir y caducan en :hours horas. Cada uno sirve solo para este registro.',
         'open' => 'Abrir',
+        'opens_new_tab' => '(se abre en una pestaña nueva)',
+        'link_for' => 'Enlace de vista previa en :language',
     ],
 
     'trash' => [