feat(bridge): alt(331f) 写通道——build 4 + CLI raw --channel alt，测试全绿

src/ppclock/cli.py

@@ -172,7 +172,7 @@ def build_parser() -> argparse.ArgumentParser:
 
     sp = sub.add_parser("raw", help="高级命令：直发 hex")
     sp.add_argument("hex")
-    sp.add_argument("--channel", default="rxtx", choices=["rxtx", "epd"])
+    sp.add_argument("--channel", default="rxtx", choices=["rxtx", "epd", "alt"])
     sp.add_argument("--no-response", action="store_true")
 
     sp = sub.add_parser("ota", help="SUOTA 固件升级（高危，需确认）")
@@ -255,6 +255,8 @@ async def _run_command(args, t):
         data = bytes.fromhex(args.hex)
         if args.channel == "epd":
             await t.write_epd(data, response=not args.no_response)
+        elif args.channel == "alt":
+            await t.write_alt(data, response=not args.no_response)
         else:
             await t.write_rxtx(data, response=not args.no_response)
         return {"sent": len(data)}