fix(telegram): pass parentPeer for forum topic binding inheritance (#9789)

Fixes #9545 and #9351.

When a message comes from a Telegram forum topic, the peer ID includes
the topic suffix (e.g., `-1001234567890:topic:99`). Users configure
bindings with the base group ID, which previously did not match.

This adds `parentPeer` to `resolveAgentRoute()` calls for forum groups,
enabling binding inheritance from the parent group to all topics.

- Extract `buildTelegramParentPeer()` helper in bot/helpers.ts
- Pass parentPeer in bot-message-context.ts, bot-handlers.ts,
  bot-native-commands.ts, and bot.ts (reaction handler)
- Add tests for forum topic routing and topic precedence

src/telegram/bot.ts

@@ -40,6 +40,7 @@ import {
 } from "./bot-updates.js";
 import {
   buildTelegramGroupPeerId,
+  buildTelegramParentPeer,
   resolveTelegramForumThreadId,
   resolveTelegramStreamMode,
 } from "./bot/helpers.js";
@@ -444,11 +445,13 @@ export function createTelegramBot(opts: TelegramBotOptions) {
         ? resolveTelegramForumThreadId({ isForum, messageThreadId: undefined })
         : undefined;
       const peerId = isGroup ? buildTelegramGroupPeerId(chatId, resolvedThreadId) : String(chatId);
+      const parentPeer = buildTelegramParentPeer({ isGroup, resolvedThreadId, chatId });
       const route = resolveAgentRoute({
         cfg,
         channel: "telegram",
         accountId: account.accountId,
         peer: { kind: isGroup ? "group" : "dm", id: peerId },
+        parentPeer,
       });
       const sessionKey = route.sessionKey;