feat(telegram): preserve reply/quote context in delivered messages

## Problem

When a user quotes/replies to a previous message in Telegram, the quoted context is lost in delivery to the agent. The agent only receives the new message text, not the referenced message.

Example: User replies to a message saying "Deploy the OAuth middleware" with "Status now?" — the agent receives only "Status now?" with no context about what the user is asking about.

## Current Behavior

The scion Telegram bridge delivers messages as:
```json
{
"msg": "Status now?",
"type": "instruction",
"channel": "telegram"
}
```

The `reply_to_message` field from Telegram's API is not included.

## Proposed Behavior

Include the quoted message content when available:
```json
{
"msg": "Status now?",
"type": "instruction",
"channel": "telegram",
"reply_to": {
"msg": "Deploy the OAuth middleware and fix the red team vulns",
"sender": "user:dev@localhost",
"timestamp": "2026-06-19T04:45:00Z"
}
}
```

This would let the agent understand what the user is referencing without requiring them to re-paste context.

## Impact

Without this, users must redundantly include context in every message. Telegram's reply feature is a natural UX pattern that currently breaks the agent's ability to follow the conversation.

Start at the scion Telegram bridge's delivery handling and inspect how Telegram's reply_to_message field is mapped into the delivered JSON. Preserve the available quoted message content and metadata under reply_to, then verify that replied-to messages produce the proposed payload while ordinary messages remain unchanged.

Written by the indexing model from the issue text.