fix(telegram): include forward_from_chat metadata in forwarded message context (#8133)

Extract missing metadata from forwarded Telegram messages:

- Add fromChatType to TelegramForwardedContext, capturing the original
  chat type (channel/supergroup/group) from forward_from_chat.type
  and forward_origin.chat/sender_chat.type
- Add fromMessageId to capture the original message ID from channel forwards
- Read author_signature from forward_origin objects (modern API),
  preferring it over the deprecated forward_signature field
- Pass ForwardedFromChatType and ForwardedFromMessageId through to
  the inbound context payload
- Add test coverage for forward_origin channel/chat types, including
  author_signature extraction and fromChatType propagation

src/telegram/bot-message-context.ts

@@ -598,6 +598,8 @@ export const buildTelegramMessageContext = async ({
     ForwardedFromUsername: forwardOrigin?.fromUsername,
     ForwardedFromTitle: forwardOrigin?.fromTitle,
     ForwardedFromSignature: forwardOrigin?.fromSignature,
+    ForwardedFromChatType: forwardOrigin?.fromChatType,
+    ForwardedFromMessageId: forwardOrigin?.fromMessageId,
     ForwardedDate: forwardOrigin?.date ? forwardOrigin.date * 1000 : undefined,
     Timestamp: msg.date ? msg.date * 1000 : undefined,
     WasMentioned: isGroup ? effectiveWasMentioned : undefined,