fix(qqbot): treat DM chat_type same as C2C for approval buttons and message delivery

[HongChenGG]

Problem

QQ Bot adapter's only checks for , but QQ DM session keys are recorded as . This causes:

1. Approval buttons rejected — users in QQ DMs see when trying to approve agent actions
2. Message delivery failures — and don't handle chat_type, causing errors or wrong API paths

Fix

Treat the same as in 4 locations:

Location	Function	Change
Line 1095		== "c2c" → in {"c2c", "dm"}
Line 2476	_send_chunk (text)	same
Line 2603	_send_chunk (keyboard)	same
Line 2928	_send_media	same

Context

• QQ Bot's C2C private messages use and the adapter stores chat_type="c2c" in _chat_type_map
• But guild DM messages go through _handle_dm_message which stores chat_type="dm"
• The MessageEvent itself always passes chat_type="dm" for both paths
• This mismatch causes approval authorization to fail and message delivery to use wrong API paths

[liuhao1024]

The dm alias is applied consistently in 4 places (authorization check, _send_chunk, send_with_keyboard, _send_media), but two other code paths still compare against "c2c" only:

1. send_typing() (~line 3067) — if chat_type != "c2c": return silently drops typing indicators for DM sessions. When the gateway sends a typing indicator for a DM message whose chat_type was recorded as "dm", the indicator is never delivered.

2. _upload_media() (~line 2370) — if target_type == "c2c" selects the API endpoint. A DM media upload where target_type is "dm" falls through to the group endpoint (/v2/groups/{id}/files), which will fail or route to the wrong recipient.

Both should use in {"c2c", "dm"} to match the rest of the PR.

[HongChenGG]

Thanks for catching these! Fixed both:

1. send_typing(): chat_type != "c2c" → not in {"c2c", "dm"}
2. _upload_media(): target_type == "c2c" → in {"c2c", "dm"}

Also updated the docstring for send_typing to reflect DM support.