feat(i18n): add English support for host-side chat messages

Wrap all user-facing chat text in src/channels with a host-side t()
translator (Chinese is the identity default, so untranslated text is
always sent verbatim in Chinese). English is selected via the host
plugin config `language: en` or the DSH_IM_LANGUAGE environment
variable, and the settings UI keeps following the DSH web locale.

- add src/channels/shared/i18n.mjs with setImHostLanguage/t() and a
  Chinese-key -> English dictionary split by area (shared + channels)
- complete the English dictionary for every t() key in src/channels,
  including the feishu channel (welcome/help, repair flow, interactive
  cards, watch flow) and the shared command/approval/stream text
- wrap previously untranslated chat-facing strings in feishu bridge,
  feishu runtime, editable-message-stream, harness-client,
  connection-test and image-prompt
- dedupe dictionary entries that existed in multiple channel files and
  canonicalize conflicting translations into the shared dictionaries
- extend the i18n unit test to decode string-literal escapes so keys
  containing \n are checked correctly
- document the language switch in README.md, README.en.md and
  CHANGELOG.md, and rebuild lib/index.js

Added English support for bot chat messages across all nine IM
channels and AI Office without changing any Chinese output.

src/channels/slack/config-store.mjs

@@ -2,6 +2,8 @@ import { createHash } from 'node:crypto';
 import { mkdir, readFile, rename, unlink, writeFile } from 'node:fs/promises';
 import { dirname } from 'node:path';
 
+import { t } from '../shared/i18n.mjs';
+
 const EMPTY_DOCUMENT = Object.freeze({ version: 1, bots: Object.freeze([]) });
 const BOT_ID_PATTERN = /^slack_[a-f0-9]{24}$/;
 const BOT_TOKEN_REF_PATTERN = /^DSH_SLACK_BOT_TOKEN_[A-F0-9]{24}$/;
@@ -27,7 +29,7 @@ export function maskSlackBotId(platformId) {
   const value = cleanString(platformId) ?? '';
   const [teamId, userId] = value.split(':');
   if (teamId && userId) return `${teamId.slice(0, 5)}••• · ${userId.slice(0, 5)}•••`;
-  return value ? `${value.slice(0, 6)}••••` : 'Slack机器人';
+  return value ? `${value.slice(0, 6)}••••` : t('Slack机器人');
 }
 
 export class SlackConfigStore {

src/channels/slack/slack-api.mjs

@@ -1,5 +1,6 @@
 import { fetchFileStream } from '../shared/file-download.mjs';
 import { fetchImageBuffer, ImagePromptError } from '../shared/image-prompt.mjs';
+import { t } from '../shared/i18n.mjs';
 
 const DEFAULT_BASE_URL = 'https://slack.com/api/';
 const SLACK_FILE_HOST = 'files.slack.com';
@@ -430,7 +431,7 @@ export class SlackApi {
         throw new ImagePromptError(
           'slack-file-access-required',
           'Slack redirected a private file request to the workspace because file access was not granted',
-          'Slack 未授权机器人读取该文件。请为应用添加 files:read 后重新安装，再重新发送图片。',
+          t('Slack 未授权机器人读取该文件。请为应用添加 files:read 后重新安装，再重新发送图片。'),
         );
       }
       return response;
@@ -505,19 +506,19 @@ export class SlackApi {
 
 export async function inspectSlackCredentials({ botToken, appToken }, options = {}) {
   if (!validSlackBotToken(botToken)) {
-    const error = new TypeError('Slack Bot Token 必须以 xoxb- 开头。');
+    const error = new TypeError(t('Slack Bot Token 必须以 xoxb- 开头。'));
     error.code = 'slack-invalid-bot-token';
     throw error;
   }
   if (!validSlackAppToken(appToken)) {
-    const error = new TypeError('Slack App Token 必须以 xapp- 开头。');
+    const error = new TypeError(t('Slack App Token 必须以 xapp- 开头。'));
     error.code = 'slack-invalid-app-token';
     throw error;
   }
   const api = new SlackApi({ botToken, appToken, ...options });
   const [identity, connection] = await Promise.all([api.authTest(), api.openConnection()]);
   if (!identity?.team_id || !identity?.user_id || !identity?.bot_id) {
-    throw new Error('Slack Bot Token 没有返回完整的机器人身份。');
+    throw new Error(t('Slack Bot Token 没有返回完整的机器人身份。'));
   }
   let socketUrl;
   try {
@@ -526,7 +527,7 @@ export async function inspectSlackCredentials({ botToken, appToken }, options =
     socketUrl = null;
   }
   if (!socketUrl || socketUrl.protocol !== 'wss:') {
-    const error = new Error('Slack App Token 无法创建 Socket Mode 连接，请确认已启用 Socket Mode 和 connections:write。');
+    const error = new Error(t('Slack App Token 无法创建 Socket Mode 连接，请确认已启用 Socket Mode 和 connections:write。'));
     error.code = 'slack-socket-mode';
     throw error;
   }

src/channels/slack/slack-controller.mjs

@@ -1,4 +1,5 @@
 import { connectionTestMessage } from '../shared/connection-test.mjs';
+import { t } from '../shared/i18n.mjs';
 import { deriveSlackBotIdentity, maskSlackBotId } from './config-store.mjs';
 import { inspectSlackCredentials } from './slack-api.mjs';
 import { SLACK_DESCRIPTOR } from './slack-bridge.mjs';
@@ -60,7 +61,7 @@ export class SlackController {
         if (!resolved) {
           this.#errors.set(config.botId, safeError(
             'missing-token',
-            'Slack机器人凭据缺失，请移除后重新接入。',
+            t('Slack机器人凭据缺失，请移除后重新接入。'),
           ));
           return;
         }
@@ -70,7 +71,7 @@ export class SlackController {
         } catch (error) {
           this.#errors.set(config.botId, safeError(
             'connection-failed',
-            'Slack Socket Mode 连接未就绪，插件会自动重试。',
+            t('Slack Socket Mode 连接未就绪，插件会自动重试。'),
           ));
           this.#logger.warn?.(
             `[dsh-im:slack] bot ${config.botId} failed to initialize:`,
@@ -135,7 +136,7 @@ export class SlackController {
       } catch (error) {
         this.#errors.set(identity.botId, safeError(
           'connection-failed',
-          'Slack机器人已接入，Socket Mode 连接暂未就绪。',
+          t('Slack机器人已接入，Socket Mode 连接暂未就绪。'),
         ));
         this.#logger.warn?.(
           `[dsh-im:slack] bot ${identity.botId} credential connection failed:`,
@@ -159,7 +160,7 @@ export class SlackController {
       } catch (error) {
         this.#errors.set(botId, safeError(
           'connection-failed',
-          'Slack Socket Mode 连接仍未就绪，请检查两个 Token。',
+          t('Slack Socket Mode 连接仍未就绪，请检查两个 Token。'),
         ));
         throw error;
       } finally {
@@ -175,13 +176,13 @@ export class SlackController {
     return this.#withBotTransition(botId, async () => {
       const runtime = this.#runtimes.get(botId);
       if (!runtime?.status?.ready || typeof runtime.sendConnectionTest !== 'function') {
-        const error = new Error('Slack机器人尚未连接');
+        const error = new Error(t('Slack机器人尚未连接'));
         error.code = 'test-target-unavailable';
         throw error;
       }
       await runtime.sendConnectionTest(connectionTestMessage(
         `${config.name}（${maskSlackBotId(config.platformId)}）`,
-        'Slack机器人',
+        t('Slack机器人'),
       ));
       return { sent: true };
     });
@@ -243,9 +244,9 @@ export class SlackController {
         },
         health: {
           status: connected ? 'healthy' : state === 'error' ? 'error' : 'offline',
-          summary: connected ? `Slack${SLACK_DESCRIPTOR.connectionLabel}运行正常`
-            : state === 'error' ? 'Slack连接未就绪，插件会自动重试'
-              : 'Slack连接当前离线',
+          summary: connected ? t(`Slack${SLACK_DESCRIPTOR.connectionLabel}运行正常`)
+            : state === 'error' ? t('Slack连接未就绪，插件会自动重试')
+              : t('Slack连接当前离线'),
           lastCheckedAt: runtimeStatus?.lastCheckedAt ?? null,
           lastConnectedAt: runtimeStatus?.lastConnectedAt ?? null,
         },

src/channels/slack/slack-runtime.mjs

@@ -1,4 +1,5 @@
 import { splitMessageText } from '../shared/editable-message-stream.mjs';
+import { t } from '../shared/i18n.mjs';
 import { SlackApi } from './slack-api.mjs';
 import { createSlackBridgeStatus, SlackHarnessBridge } from './slack-bridge.mjs';
 
@@ -217,7 +218,7 @@ async function createSlackMessageStream({ api, target, signal, logger }) {
       await inFlight?.catch(() => undefined);
 
       const chunks = splitMessageText(text, SLACK_MESSAGE_LIMIT);
-      const first = chunks[0] ?? '处理完成。';
+      const first = chunks[0] ?? t('处理完成。');
       if (!broken && first.startsWith(appended)) {
         await appendInChunks(api, target, ts, first.slice(appended.length), signal);
         await api.stopStream({ channelId: target.channelId, ts, signal });