Refactor Akaunting role and CSP handling

- Improved CSP filter to properly include web-svc-cdn and use protocol-aware domains
- Added Todo.md with redis and OIDC notes
- Enhanced Akaunting role config with CSP flags and redis option
- Updated schema to include app_key validation
- Reworked tasks to handle first-run marker logic cleanly
- Fixed docker-compose template (marker, healthcheck, setup flag)
- Expanded env.j2 with cache, email, proxy, and redis options
- Added javascript.js.j2 template for SSO warning
- Introduced structured vars for Akaunting role
- Removed deprecated update-repository-with-files.yml task

See conversation: https://chatgpt.com/share/68af00df-2c74-800f-90b6-6ac5b29acdcb

roles/web-app-akaunting/schema/main.yml

@@ -2,4 +2,8 @@ credentials:
   setup_admin_password:
     description: "Initial admin user password for Akaunting"
     algorithm: "sha256"
-    validation: "^[a-f0-9]{64}$"
+    validation: "^[a-f0-9]{64}$"
+  app_key:
+    description: "Laravel application key (base64 encoded 32-byte key, prefixed with 'base64:')"
+    algorithm: "base64_prefixed_32"
+    validation: "^base64:[A-Za-z0-9+/=]{43,}$"