Complete TASK_CHECKUP: security, UX, tests, coverage, accessibility, config externalization

Billetterie:
- Partial refund support (STATUS_PARTIALLY_REFUNDED, refundedAmount field, migration)
- Race condition fix: PESSIMISTIC_WRITE lock on stock decrement in transaction
- Idempotency key on PaymentIntent::create, reuse existing PI if stripeSessionId set
- Disable checkout when event ended (server 400 + template hide)
- Webhook deduplication via cache (24h TTL on stripe event.id)
- Email validation (filter_var) in OrderController guest flow
- JSON cart validation (structure check before processing)
- Invitation expiration after 7 days (isExpired method + landing page message)
- Stripe Checkout fallback when JS fails to load (noscript + redirect)

Config externalization:
- Move Stripe fees (STRIPE_FEE_RATE, STRIPE_FEE_FIXED) and admin email (ADMIN_EMAIL) to .env/services.yaml
- Replace all hardcoded contact@e-cosplay.fr across 13 files
- MailerService: getAdminEmail()/getAdminFrom(), default $from=null resolves to admin

UX & Accessibility:
- ARIA tabs: role=tablist/tab/tabpanel, aria-selected, keyboard nav (arrows, Home, End)
- aria-label on cart +/- buttons and editor toolbar buttons
- tabindex=0 on editor toolbar buttons for keyboard access
- data-confirm handler in app.js (was only in admin.js)
- Cart error feedback on checkout failure
- Billet designer save feedback (loading/success/error states)
- Stock polling every 30s with rupture/low stock badges
- Back to event link on payment page

Security:
- HTML sanitizer: BLOCKED_TAGS list (script, style, iframe, svg, etc.) - content fully removed
- Stripe polling timeout (15s max) with fallback redirect
- Rate limiting on public order access (20/5min)
- .catch() on all fetch() calls (sortable, billet-designer)

Tests (92% PHP, 100% JS lines):
- PCOV added to dev Dockerfile
- Test DB setup: .env.test with DATABASE_URL, Redis auth, Meilisearch key
- Rate limiter disabled in test env
- Makefile: test_db_setup, test_db_reset, run_test_php, run_test_coverage_php/js
- New tests: InvitationFlowTest (21), AuditServiceTest (4), ExportServiceTest (9), InvoiceServiceTest (4)
- New tests: SuspendedUserSubscriberTest, RateLimiterSubscriberTest, MeilisearchServiceTest
- New tests: Stripe webhook payment_failed (6) + charge.refunded (6)
- New tests: BilletBuyer refund, User suspended, OrganizerInvitation expiration
- JS tests: stock polling (6), data-confirm (2), copy-url restore (1), editor ARIA (2), XSS (9), tabs keyboard (9)
- ESLint + PHP CS Fixer: 0 errors
- SonarQube exclusions aligned with vitest coverage config

Infra:
- Meilisearch consistency command (app:meilisearch:check-consistency --fix) + cron daily 3am
- MeilisearchService: getAllDocumentIds(), listIndexes()

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.env.test

@@ -1,11 +1,16 @@
 # define your env variables for the test env here
 KERNEL_CLASS='App\Kernel'
 APP_SECRET='$ecretf0rt3st'
+DATABASE_URL="postgresql://app:secret@database:5432/e_ticket?serverVersion=16&charset=utf8"
 MEILISEARCH_URL=http://meilisearch:7700
-MEILISEARCH_API_KEY=test
+MEILISEARCH_API_KEY=e_ticket
 SONARQUBE_URL=https://sn.esy-web.dev
 SONARQUBE_BADGE_TOKEN=test
 SONARQUBE_PROJECT_KEY=e-ticket
 STRIPE_SK=sk_test_fake
 STRIPE_WEBHOOK_SECRET=whsec_test
+STRIPE_WEBHOOK_SECRET_CONNECT=whsec_test_connect
 OUTSIDE_URL=https://test.example.com
+MESSENGER_TRANSPORT_DSN=redis://:e_ticket@redis:6379/messages
+SMIME_PASSPHRASE=test
+ADMIN_EMAIL=contact@test.com