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-message-context.ts

@@ -45,6 +45,7 @@ import {
   buildSenderName,
   buildTelegramGroupFrom,
   buildTelegramGroupPeerId,
+  buildTelegramParentPeer,
   buildTypingThreadParams,
   expandTextLinks,
   normalizeForwardedContext,
@@ -161,6 +162,7 @@ export const buildTelegramMessageContext = async ({
   const replyThreadId = threadSpec.id;
   const { groupConfig, topicConfig } = resolveTelegramGroupConfig(chatId, resolvedThreadId);
   const peerId = isGroup ? buildTelegramGroupPeerId(chatId, resolvedThreadId) : String(chatId);
+  const parentPeer = buildTelegramParentPeer({ isGroup, resolvedThreadId, chatId });
   const route = resolveAgentRoute({
     cfg,
     channel: "telegram",
@@ -169,6 +171,7 @@ export const buildTelegramMessageContext = async ({
       kind: isGroup ? "group" : "dm",
       id: peerId,
     },
+    parentPeer,
   });
   const baseSessionKey = route.sessionKey;
   // DMs: use raw messageThreadId for thread sessions (not forum topic ids)