docs: update README and add pre-commit hook (#173)

* docs: replace requirements with developer and deployment guide

* docs: add CI badge, disclaimer, contributing guide, and license

* docs: fix and expand disclaimer based on legal review

* docs: clarify test vs dev fixture commands in testing section

* feat: add pre-commit hook for staged-file quality checks

Adds a versioned .githooks/pre-commit script that runs Rector,
PHP-CS-Fixer, and PHPStan on staged PHP files, and Twig-CS-Fixer on
staged Twig files. Auto-fixes are re-staged before PHPStan runs.
Falls back to docker compose run --rm when the PHP service is not up.

Install with: just install-hooks

* chore: switch pre-commit hook shebang from bash to zsh

Justfile

@@ -51,6 +51,11 @@ reload-tests:
     @docker compose exec php bin/console --env=test doctrine:migrations:migrate -n
     @docker compose exec php bin/console --env=test doctrine:fixtures:load -n --group=test
 
+install-hooks:
+    git config core.hooksPath .githooks
+    chmod +x .githooks/pre-commit
+    @echo "Pre-commit hook installed."
+
 trust-cert:
     sudo security add-trusted-cer -d \
     -r trustRoot \