feat(channels): 社交渠道 OAuth 改进 + 集成应用重命名 + AI 流程文档

- Facebook/Instagram/TikTok 渠道 OAuth 授权流程改进
- 新增 oauth/credentialstore 包
- 集成应用 OpenAI 重命名为 OpenAI 兼容 (migration 061)
- 消息生命周期与 AI 流程架构文档
- inbox 管理界面 i18n 更新

backend/internal/handler/api/v1/integration_hook_handler.go

@@ -266,7 +266,9 @@ func integrationAppSettingsFormSchema(appID string) []gin.H {
 	schemas := map[string][]gin.H{
 		"openai": {
 			{"label": "API Key", "type": "text", "name": "api_key", "validation": "required"},
-			{"label": "Show label suggestions", "type": "checkbox", "name": "label_suggestion", "validation": ""},
+			{"label": "Base URL", "type": "text", "name": "base_url", "validation": "required", "help": "OpenAI 兼容 API 地址，例如 https://api.openai.com/v1"},
+			{"label": "模型", "type": "text", "name": "model", "validation": "required", "help": "自定义模型名称，例如 gpt-4o-mini、deepseek-chat 等"},
+			{"label": "启用标签建议", "type": "checkbox", "name": "label_suggestion", "validation": "", "help": "勾选后，在对话视图中显示 AI 生成的标签建议"},
 		},
 		"dialogflow": {
 			{"label": "Dialogflow Project ID", "type": "text", "name": "project_id", "validation": "required", "validationName": "Project Id"},
@@ -297,7 +299,7 @@ func integrationAppSettingsFormSchema(appID string) []gin.H {
 
 func integrationAppVisibleProperties(appID string) []string {
 	properties := map[string][]string{
-		"openai":           {"api_key", "label_suggestion"},
+		"openai":           {"api_key", "base_url", "model", "label_suggestion"},
 		"dialogflow":       {"project_id", "region", "language_code"},
 		"google_translate": {"project_id"},
 		"dyte":             {"organization_id"},