ops(ci): trigger CI on main pushes + disable auto deploy-staging Phase 0

- CI runs on push to main + develop + PR (was: ignore main → never ran on main)
- Deploy staging : workflow_dispatch only (re-activer push trigger quand
  secrets STAGING_HOST/USER/SSH_KEY configures cote GitHub)

Effet : push suivant trigger un CI complet et verifie que la stack passe les
gates avant tout deploy.

.github/workflows/ci.yml

@@ -2,9 +2,10 @@ name: CI
 
 on:
   push:
-    branches-ignore: [main]
+    branches: [main, develop]
   pull_request:
     branches: [main]
+  workflow_dispatch:
 
 permissions:
   contents: read

.github/workflows/deploy-staging.yml

@@ -1,9 +1,10 @@
 name: Deploy Staging
 
 on:
-  push:
+  # Phase 0 : workflow_dispatch only — re-activer le push trigger quand secrets STAGING_* configures
-    branches: [main]
   workflow_dispatch:
+  # push:
+  #   branches: [main]
 
 permissions:
   contents: read