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-native-commands.ts

@@ -50,6 +50,7 @@ import {
   buildSenderName,
   buildTelegramGroupFrom,
   buildTelegramGroupPeerId,
+  buildTelegramParentPeer,
   resolveTelegramForumThreadId,
   resolveTelegramThreadSpec,
 } from "./bot/helpers.js";
@@ -469,6 +470,7 @@ export const registerTelegramNativeCommands = ({
             });
             return;
           }
+          const parentPeer = buildTelegramParentPeer({ isGroup, resolvedThreadId, chatId });
           const route = resolveAgentRoute({
             cfg,
             channel: "telegram",
@@ -477,6 +479,7 @@ export const registerTelegramNativeCommands = ({
               kind: isGroup ? "group" : "dm",
               id: isGroup ? buildTelegramGroupPeerId(chatId, resolvedThreadId) : String(chatId),
             },
+            parentPeer,
           });
           const baseSessionKey = route.sessionKey;
           // DMs: use raw messageThreadId for thread sessions (not resolvedThreadId which is for forums)