Add health check endpoint and resolve locale detection bug (#387)

* Add health check API endpoint with database connectivity

* Update locale handling to fallback to default language on invalid input

* Add health check endpoints for application readiness and liveness

- Introduced `/api/health/readiness` endpoint to check if the application can serve requests, including database connectivity.
- Introduced `/api/health/liveness` endpoint to verify if the application is running independently of external dependencies.
- Updated the health check logic to streamline database connectivity checks and response handling.

* Refactor health check logic

---------

Co-authored-by: Julen Dixneuf <julen.d@padoa-group.com>

src/app/api/health/liveness/route.ts

@@ -0,0 +1,7 @@
+import { checkLiveness } from '@/lib/health'
+
+// Liveness: Is the app itself healthy? (no external dependencies)
+// If this fails, Kubernetes should restart the pod
+export async function GET() {
+  return checkLiveness()
+}

src/app/api/health/readiness/route.ts

@@ -0,0 +1,7 @@
+import { checkReadiness } from '@/lib/health'
+
+// Readiness: Can the app serve requests? (includes all external dependencies)
+// If this fails, Kubernetes should stop sending traffic but not restart
+export async function GET() {
+  return checkReadiness()
+}

src/app/api/health/route.ts

@@ -0,0 +1,7 @@
+import { checkReadiness } from '@/lib/health'
+
+// Default health check - same as readiness (includes database check)
+// This is readiness-focused for monitoring tools like uptime-kuma
+export async function GET() {
+  return checkReadiness()
+}