refactor(qqbot): split qqbot.py into package & add QR scan-to-configure onboard flow

- Refactor gateway/platforms/qqbot.py into gateway/platforms/qqbot/ package:
  - adapter.py: core QQAdapter (unchanged logic, constants from shared module)
  - constants.py: shared constants (API URLs, timeouts, message types)
  - crypto.py: AES-256-GCM key generation and secret decryption
  - onboard.py: QR-code scan-to-configure API (create_bind_task, poll_bind_result)
  - utils.py: User-Agent builder, HTTP headers, config helpers
  - __init__.py: re-exports all public symbols for backward compatibility

- Add interactive QR-code setup flow in hermes_cli/gateway.py:
  - Terminal QR rendering via qrcode package (graceful fallback to URL)
  - Auto-refresh on QR expiry (up to 3 times)
  - AES-256-GCM encrypted credential exchange
  - DM security policy selection (pairing/allowlist/open)

- Update hermes_cli/setup.py to delegate to gateway's _setup_qqbot()
- Add qrcode>=7.4 dependency to pyproject.toml and requirements.txt

gateway/platforms/qqbot/utils.py

@@ -0,0 +1,71 @@
+"""QQBot shared utilities — User-Agent, HTTP helpers, config coercion."""
+
+from __future__ import annotations
+
+import platform
+import sys
+from typing import Any, Dict, List
+
+from .constants import QQBOT_VERSION
+
+
+# ---------------------------------------------------------------------------
+# User-Agent
+# ---------------------------------------------------------------------------
+
+def _get_hermes_version() -> str:
+    """Return the hermes-agent package version, or 'dev' if unavailable."""
+    try:
+        from importlib.metadata import version
+        return version("hermes-agent")
+    except Exception:
+        return "dev"
+
+
+def build_user_agent() -> str:
+    """Build a descriptive User-Agent string.
+
+    Format::
+
+        QQBotAdapter/<qqbot_version> (Python/<py_version>; <os>; Hermes/<hermes_version>)
+
+    Example::
+
+        QQBotAdapter/1.0.0 (Python/3.11.15; darwin; Hermes/0.9.0)
+    """
+    py_version = f"{sys.version_info.major}.{sys.version_info.minor}.{sys.version_info.micro}"
+    os_name = platform.system().lower()
+    hermes_version = _get_hermes_version()
+    return f"QQBotAdapter/{QQBOT_VERSION} (Python/{py_version}; {os_name}; Hermes/{hermes_version})"
+
+
+def get_api_headers() -> Dict[str, str]:
+    """Return standard HTTP headers for QQBot API requests.
+
+    Includes ``Content-Type``, ``Accept``, and a dynamic ``User-Agent``.
+    ``q.qq.com`` requires ``Accept: application/json`` — without it,
+    the server returns a JavaScript anti-bot challenge page.
+    """
+    return {
+        "Content-Type": "application/json",
+        "Accept": "application/json",
+        "User-Agent": build_user_agent(),
+    }
+
+
+# ---------------------------------------------------------------------------
+# Config helpers
+# ---------------------------------------------------------------------------
+
+def coerce_list(value: Any) -> List[str]:
+    """Coerce config values into a trimmed string list.
+
+    Accepts comma-separated strings, lists, tuples, sets, or single values.
+    """
+    if value is None:
+        return []
+    if isinstance(value, str):
+        return [item.strip() for item in value.split(",") if item.strip()]
+    if isinstance(value, (list, tuple, set)):
+        return [str(item).strip() for item in value if str(item).strip()]
+    return [str(value).strip()] if str(value).strip() else []