feat(tgbot): route admin notifications to a forum topic (#6879)

Admins who run the bot in a forum supergroup got every notification in the
General topic. An admin chat ID may now carry a topic, chatId:topicId, and the
bot's admin messages and reports go to that topic. Repeated chats collapse into
one entry and a second, different topic for the same chat is rejected, in the
panel and in the docs setup helper alike. The chat ID hint in every locale and
the English, Persian, Russian and Chinese guides describe the form.

docs/content/docs/en/operations/telegram-bot.mdx

@@ -37,6 +37,11 @@ connected). This is your **admin** ID.
 
 In Panel Settings, enable the Telegram bot and set the **token** and **admin chat
 ID(s)** (comma-separated). Save, then message your bot.
+
+To send notifications into a specific topic of a forum supergroup, append the
+topic ID after a colon, e.g. `-1001234567890:42`. The topic ID is the number
+after the chat in a topic message link (`https://t.me/c/1234567890/42/…`). Leave
+the topic off (or use `1`) for the General topic.
 </Step>
 
 </Steps>
@@ -101,7 +106,7 @@ The warning lead times come from `expireDiff` (days before expiry) and
 | -------------- | -------------------------- | ---------------------------------------------- |
 | `tgBotEnable`  | `false`                    | Master on/off.                                 |
 | `tgBotToken`   | _(secret)_                 | Bot API token.                                 |
-| `tgBotChatId`  | _(none)_                   | Comma-separated **admin** Telegram IDs.        |
+| `tgBotChatId`  | _(none)_                   | Comma-separated **admin** Telegram IDs; `chatId:topicId` targets a forum topic. |
 | `tgBotProxy`   | _(none)_                   | `socks5://`, `http://`, or `https://` proxy.   |
 | `tgBotAPIServer` | _(default)_              | Custom Telegram Bot API server.                |
 | `tgRunTime`    | `@daily`                   | Report schedule (cron / `@daily` / `@every …`).|