#7407: feat(telegram): human-readable topic names in session dropdown

## Summary Session dropdown now shows human-readable topic names instead of raw numeric IDs for Telegram forum topics. **Before:** `agent:main:telegram:group:-123245:topic:45` **After:** `Telegram : GroupName : TopicName` ## Changes - **src/telegram/bot-message-context.ts** - Extract topic name from `forum_topic_created` service messages - **src/auto-reply/templating.ts** - Add `TopicName` field - **src/config/sessions/types.ts** - Add `topicName` field to session metadata - **src/config/sessions/metadata.ts** - Store `topicName` when available - **src/config/sessions/group.ts** - Telegram-specific display format with spaced colons - **src/config/sessions.test.ts** - Test coverage **Note:** Telegram-specific implementation. Format uses spaced colons for readability. Fixes #7406