feat(openai): 增加 gpt-5.4-mini/nano 模型支持与定价配置

- 接入 gpt-5.4-mini/nano 模型识别与规范化，补充默认模型列表
- 增加 gpt-5.4-mini/nano 输入/缓存命中/输出价格与计费兜底逻辑
- 同步前端模型白名单与 OpenCode 配置
- 补充 service tier(priority/flex) 计费回归测试

frontend/src/components/keys/UseKeyModal.vue

@@ -705,6 +705,38 @@ function generateOpenCodeConfig(platform: string, baseUrl: string, apiKey: strin
         xhigh: {}
       }
     },
+    'gpt-5.4-mini': {
+      name: 'GPT-5.4 Mini',
+      limit: {
+        context: 400000,
+        output: 128000
+      },
+      options: {
+        store: false
+      },
+      variants: {
+        low: {},
+        medium: {},
+        high: {},
+        xhigh: {}
+      }
+    },
+    'gpt-5.4-nano': {
+      name: 'GPT-5.4 Nano',
+      limit: {
+        context: 400000,
+        output: 128000
+      },
+      options: {
+        store: false
+      },
+      variants: {
+        low: {},
+        medium: {},
+        high: {},
+        xhigh: {}
+      }
+    },
     'gpt-5.3-codex-spark': {
       name: 'GPT-5.3 Codex Spark',
       limit: {

frontend/src/components/keys/__tests__/UseKeyModal.spec.ts

@@ -0,0 +1,53 @@
+import { describe, expect, it, vi } from 'vitest'
+import { mount } from '@vue/test-utils'
+import { nextTick } from 'vue'
+
+vi.mock('vue-i18n', () => ({
+  useI18n: () => ({
+    t: (key: string) => key
+  })
+}))
+
+vi.mock('@/composables/useClipboard', () => ({
+  useClipboard: () => ({
+    copyToClipboard: vi.fn().mockResolvedValue(true)
+  })
+}))
+
+import UseKeyModal from '../UseKeyModal.vue'
+
+describe('UseKeyModal', () => {
+  it('renders updated GPT-5.4 mini/nano names in OpenCode config', async () => {
+    const wrapper = mount(UseKeyModal, {
+      props: {
+        show: true,
+        apiKey: 'sk-test',
+        baseUrl: 'https://example.com/v1',
+        platform: 'openai'
+      },
+      global: {
+        stubs: {
+          BaseDialog: {
+            template: '<div><slot /><slot name="footer" /></div>'
+          },
+          Icon: {
+            template: '<span />'
+          }
+        }
+      }
+    })
+
+    const opencodeTab = wrapper.findAll('button').find((button) =>
+      button.text().includes('keys.useKeyModal.cliTabs.opencode')
+    )
+
+    expect(opencodeTab).toBeDefined()
+    await opencodeTab!.trigger('click')
+    await nextTick()
+
+    const codeBlock = wrapper.find('pre code')
+    expect(codeBlock.exists()).toBe(true)
+    expect(codeBlock.text()).toContain('"name": "GPT-5.4 Mini"')
+    expect(codeBlock.text()).toContain('"name": "GPT-5.4 Nano"')
+  })
+})

frontend/src/composables/__tests__/useModelWhitelist.spec.ts

@@ -11,6 +11,8 @@ describe('useModelWhitelist', () => {
     const models = getModelsByPlatform('openai')
 
     expect(models).toContain('gpt-5.4')
+    expect(models).toContain('gpt-5.4-mini')
+    expect(models).toContain('gpt-5.4-nano')
     expect(models).toContain('gpt-5.4-2026-03-05')
   })
 
@@ -52,4 +54,13 @@ describe('useModelWhitelist', () => {
       'gpt-5.4-2026-03-05': 'gpt-5.4-2026-03-05'
     })
   })
+
+  it('whitelist keeps GPT-5.4 mini and nano exact mappings', () => {
+    const mapping = buildModelMappingObject('whitelist', ['gpt-5.4-mini', 'gpt-5.4-nano'], [])
+
+    expect(mapping).toEqual({
+      'gpt-5.4-mini': 'gpt-5.4-mini',
+      'gpt-5.4-nano': 'gpt-5.4-nano'
+    })
+  })
 })

frontend/src/composables/useModelWhitelist.ts

@@ -25,7 +25,7 @@ const openaiModels = [
   'gpt-5.2', 'gpt-5.2-2025-12-11', 'gpt-5.2-chat-latest',
   'gpt-5.2-codex', 'gpt-5.2-pro', 'gpt-5.2-pro-2025-12-11',
   // GPT-5.4 系列
-  'gpt-5.4', 'gpt-5.4-2026-03-05',
+  'gpt-5.4', 'gpt-5.4-mini', 'gpt-5.4-nano', 'gpt-5.4-2026-03-05',
   // GPT-5.3 系列
   'gpt-5.3-codex', 'gpt-5.3-codex-spark',
   'chatgpt-4o-latest',