fix(n8n): drop Telegram fromId fallback — silently misrouted group chats

`meta.fromId` is the Telegram sender's *user* id, which equals the chat
id only in private 1:1 DMs. In group chats / channels the chat id is a
distinct (typically negative) integer. Falling back to fromId silently
routed group-chat workflows back to the user's DM instead of the group
(Greptile P1).

Drop the fallback. Only use the canonical `metadata.telegram.chatId`.
If the upstream Telegram plugin hasn't populated that yet (pre-existing
schema gap — flat `metadata.fromId` is the de-facto inbound shape today
for Telegram), Telegram routing is skipped rather than guessed. Discord
and Slack routing are unaffected.

Author: 2-A-M

packages/app-core/src/api/n8n-routes.ts

@@ -695,13 +695,17 @@ async function buildTriggerContextFromConversation(
   const discordThreadId =
     typeof discord.threadId === "string" ? discord.threadId : undefined;
 
+  // No `meta.fromId` fallback for Telegram: `fromId` is the sender's user
+  // id, which equals the chat id only in private 1:1 DMs. In group chats /
+  // channels the chat id is a distinct (typically negative) integer, so
+  // falling back to fromId would silently route the workflow to the wrong
+  // entity. Only use the canonical `metadata.telegram.chatId`. If the
+  // upstream Telegram plugin hasn't populated it yet, we skip Telegram
+  // routing rather than guess.
   const telegramChatId =
-    (typeof telegram.chatId === "string" || typeof telegram.chatId === "number"
+    typeof telegram.chatId === "string" || typeof telegram.chatId === "number"
       ? telegram.chatId
-      : undefined) ??
-    (typeof meta.fromId === "string" || typeof meta.fromId === "number"
-      ? (meta.fromId as string | number)
-      : undefined);
+      : undefined;
   const telegramThreadId =
     typeof telegram.threadId === "string" ||
     typeof telegram.threadId === "number"