revert: completely remove Sora platform

[touwaeriol]

背景 / Background

Sora（OpenAI 视频/图片生成平台）功能已不再使用，相关代码增加了维护负担和代码复杂度。

Sora (OpenAI video/image generation platform) functionality is no longer in use. The related code adds maintenance burden and increases codebase complexity.

---

目的 / Purpose

完全移除 Sora 平台的所有代码，包括前端 UI、后端服务、数据库 schema 和迁移脚本。

Completely remove all Sora platform code, including frontend UI, backend services, database schema, and migration scripts.

---

改动内容 / Changes

后端 / Backend

• 服务层: 删除 sora_account_service, sora_client, sora_gateway_service, sora_generation_service, sora_media_*, sora_quota_service, sora_s3_storage, sora_sdk_client, sora_upstream_forwarder 等 14 个服务文件
• 处理器层: 删除 sora_client_handler, sora_gateway_handler, sora_videos_handler
• 仓储层: 删除 sora_account_repo, sora_generation_repo, sora_task_repo
• 路由: 删除 Sora gateway 路由 (/sora/v1/*), Sora OAuth 路由, Sora S3 设置路由
• 网关调度: 从 gateway_service.go 移除 Sora 调度/计费/模型匹配逻辑
• 计费: 从 billing_service.go 移除 SoraPriceConfig, CalculateSoraImageCost, CalculateSoraVideoCost
• OAuth: 从 openai_oauth_service.go 移除 Sora session token 交换
• 配置: 从 config.go 移除 SoraConfig, SoraClientConfig 等结构体
• DI: 从 wire_gen.go 移除所有 Sora 依赖注入
• Ent Schema: 从 group/user/usage_log 移除 Sora 字段，重新生成 ent 代码
• 迁移: 新增 090_drop_sora.sql 删除 sora_tasks, sora_generations, sora_accounts 表及相关字段

---

• Service layer: Delete 14 sora_* service files (account, client, gateway, generation, media, quota, s3, sdk, upstream forwarder)
• Handler layer: Delete sora_client_handler, sora_gateway_handler, sora_videos_handler
• Repository layer: Delete sora_account_repo, sora_generation_repo, sora_task_repo
• Routes: Remove Sora gateway routes (/sora/v1/*), OAuth routes, S3 settings routes
• Gateway scheduling: Remove Sora scheduling/billing/model matching from gateway_service.go
• Billing: Remove SoraPriceConfig, CalculateSoraImageCost, CalculateSoraVideoCost
• OAuth: Remove Sora session token exchange from openai_oauth_service.go
• Config: Remove SoraConfig, SoraClientConfig structs
• DI: Remove all Sora dependency injection from wire_gen.go
• Ent Schema: Remove Sora fields from group/user/usage_log, regenerate ent code
• Migration: Add 090_drop_sora.sql to drop sora_tasks, sora_generations, sora_accounts tables

前端 / Frontend

• 视图/组件: 删除 SoraView, SoraGeneratePage, SoraMediaPreview, SoraProgressCard, SoraPromptBar, SoraQuotaBar 等 14 个文件
• API: 删除 sora.ts API 客户端和 Sora S3 设置 API
• 类型: 从 types/index.ts 移除 Sora 类型定义和平台枚举
• i18n: 移除所有 Sora 相关国际化键
• 组件清理: 从 GroupsView, SettingsView, AccountModals, PlatformIcon 等移除 Sora 引用

---

• Views/Components: Delete SoraView, SoraGeneratePage, SoraMediaPreview, SoraProgressCard, SoraPromptBar, SoraQuotaBar (14 files)
• API: Delete sora.ts client and Sora S3 settings API
• Types: Remove Sora type definitions and platform enum from types/index.ts
• i18n: Remove all Sora-related internationalization keys
• Component cleanup: Remove Sora references from GroupsView, SettingsView, AccountModals, PlatformIcon, etc.