refactor(mcp): complete form refactoring for unified MCP management

Complete the v3.7.0 MCP refactoring by updating the form layer to match
the unified architecture already implemented in data/service/API layers.

**Breaking Changes:**
- Remove confusing `appId` parameter from McpFormModal
- Replace with `defaultFormat` (json/toml) and `defaultEnabledApps` (array)

**Form Enhancements:**
- Add app enablement checkboxes (Claude/Codex/Gemini) directly in the form
- Smart defaults: new servers default to Claude enabled, editing preserves state
- Support "draft" mode: servers can be created without enabling any apps

**Architecture Improvements:**
- Eliminate semantic confusion: format selection separate from app targeting
- One-step workflow: configure and enable apps in single form submission
- Consistent with unified backend: `apps: { claude, codex, gemini }`

**Testing:**
- Update test mocks to use `useUpsertMcpServer` hook
- Add test case for creating servers with no apps enabled
- Fix parameter references from `appId` to `defaultFormat`

**i18n:**
- Add `mcp.form.enabledApps` translation (zh/en)
- Add `mcp.form.noAppsWarning` translation (zh/en)

This completes the MCP management refactoring, ensuring all layers
(data, service, API, UI) follow the same unified architecture pattern.

src/i18n/locales/en.json

@@ -478,6 +478,8 @@
       "titlePlaceholder": "my-mcp-server",
       "name": "Display Name",
       "namePlaceholder": "e.g. @modelcontextprotocol/server-time",
+      "enabledApps": "Enable to Apps",
+      "noAppsWarning": "At least one app must be selected",
       "description": "Description",
       "descriptionPlaceholder": "Optional description",
       "tags": "Tags (comma separated)",

src/i18n/locales/zh.json

@@ -478,6 +478,8 @@
       "titlePlaceholder": "my-mcp-server",
       "name": "显示名称",
       "namePlaceholder": "例如 @modelcontextprotocol/server-time",
+      "enabledApps": "启用到应用",
+      "noAppsWarning": "至少选择一个应用",
       "description": "描述",
       "descriptionPlaceholder": "可选的描述信息",
       "tags": "标签（逗号分隔）",