feat(fw): live streaming sniff with button-toggle pause/resume

Add CMD_HF_SNIFF_STREAM (0x0337) and CMD_HF_SNIFF_STATUS (0x0338) for
fire-and-forget trace streaming during sniff. Unified sniff loop uses
the same proven decode path for both streaming and legacy modes —
streaming replaces LogTrace with ring buffer SNIFF_PUSH/SNIFF_FLUSH.

Firmware features:
- Idle flush: sends buffered trace entries over USB when RF is quiet
  for idle_timeout_ms (configurable, default 400ms for 15693)
- Button-toggle: pause/resume sniffing without restarting
- DMA restart on resume for clean decoder state
- BREAK_LOOP support for Python-side session.stop()
- Legacy mode (flags=0) preserved unchanged

Python constants: SNIFF_FLAG_STREAMING, SNIFF_FLAG_BUTTON_TOGGLE,
SNIFF_STATE_STARTED/PAUSED/RESUMED/STOPPED, Cmd.HF_SNIFF_STREAM/STATUS

pm3py/core/protocol.py

@@ -202,6 +202,9 @@ class Cmd(IntEnum):
     HF_ISO15693_CSETUID = 0x0316
     HF_ISO15693_EML_SETMEM = 0x0331
 
+    HF_SNIFF_STREAM = 0x0337
+    HF_SNIFF_STATUS = 0x0338
+
     # Sim table commands (firmware response table)
     SIM_TABLE_UPLOAD = 0x0900
     SIM_TABLE_CLEAR = 0x0901
@@ -265,3 +268,14 @@ class Cmd(IntEnum):
     FPGAMEM_DOWNLOADED = 0x0803
 
     UNKNOWN = 0xFFFF
+
+
+# Sniff streaming flags
+SNIFF_FLAG_STREAMING = 0x01
+SNIFF_FLAG_BUTTON_TOGGLE = 0x02
+
+# Sniff states
+SNIFF_STATE_STARTED = 0
+SNIFF_STATE_PAUSED = 1
+SNIFF_STATE_RESUMED = 2
+SNIFF_STATE_STOPPED = 3