feat: add controller-side healthcheck configs to all 52 apps

Each app template now declares a healthcheck: section in .felhom.yml
with appropriate probe type (http, api, or tcp) and endpoint based on
the app's known health endpoints. The controller uses these to verify
services are actually responding, not just that containers are running.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

templates/privatebin/.felhom.yml

@@ -49,3 +49,9 @@ app_info:
     - 'Írd be a szöveget és kattints a Küldés gombra'
     - 'Oszd meg a generált linket - a titkosítási kulcs az URL-ben van'
 
+
+# --- Controller-side health probe ---
+healthcheck:
+  checks:
+    - type: http
+      port: 8080