feat(server): support installable license (#12181)

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit

- **New Features**
  - Added support for installing self-hosted team licenses via encrypted license files.
  - Introduced a new "Onetime" license variant for self-hosted environments.
  - Added a GraphQL mutation to upload and install license files.
  - License details now display the license variant.

- **Bug Fixes**
  - Improved error messages for license activation and expiration, including dynamic reasons.

- **Localization**
  - Updated and improved license-related error messages for better clarity.

- **Tests**
  - Added comprehensive end-to-end tests for license installation scenarios.

- **Chores**
  - Enhanced environment variable handling and public key management for license verification.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/schema.prisma

@@ -767,10 +767,12 @@ model InstalledLicense {
   workspaceId String    @unique @map("workspace_id") @db.VarChar
   quantity    Int       @default(1) @db.Integer
   recurring   String    @db.VarChar
+  variant     String?   @db.VarChar
   installedAt DateTime  @default(now()) @map("installed_at") @db.Timestamptz(3)
   validateKey String    @map("validate_key") @db.VarChar
   validatedAt DateTime  @map("validated_at") @db.Timestamptz(3)
   expiredAt   DateTime? @map("expired_at") @db.Timestamptz(3)
+  license     Bytes?    @db.ByteA
 
   @@map("installed_licenses")
 }