feat(deploy): configurable CPU/RAM/disk for app databases

Let users size the database workload from the deploy wizard the same way
Redis/RabbitMQ are configured: a resource card (CPU request/limit, memory
request/limit, storage) on the Resources step, stored in
optionalServiceResources.database.

- entity/DTO: add `database` to optionalServiceResources
- k8s: resolveDatabaseResources() applies user-selected resources on both
  the Helm and K8s-API deploy paths (was hardcoded 100m/256Mi→500m/512Mi)
- billing: bill database CPU/RAM as a separate line on top of the app's
  resources; merge it through the upgrade path too
- wizard: db resource card on the Resources step, disk moved into the card,
  cost preview + review summary include the database resources

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/i18n/dictionaries/en.ts

@@ -1231,6 +1231,8 @@ const en: Dictionary = {
       databaseCredentials: 'Database Credentials',
       dbUsername: 'DB Username', dbPassword: 'DB Password', dbStorage: 'DB Storage', dbDump: 'DB Dump',
       databaseStorageSize: 'Database Storage Size',
+      databaseResources: 'Database resources',
+      databaseResourcesHint: 'Configure the database CPU, RAM and disk on the Resources step.',
       username: 'Username', password: 'Password', autoGenerated: 'Auto-generated',
       generatePassword: 'Generate random password',
       dbCredsNote: 'These credentials are used for internal cluster communication only. The database is not exposed externally.',