Use lightweight READ_STATUS instead of full CONFIG_READ for profile polling

Live-Sync polls read_active_profile() every 1.5s, but it was requesting
a full 740-byte config dump (~124 chunk packets) just to read one
byte out of it. The firmware handles CONFIG_READ synchronously and
blocking, which delayed its LED animation update enough to make
Pulse/Blink visibly stutter on every poll cycle -- see
VersaMCU's doc/07_serial_protocol.md ("READ_STATUS vs. CONFIG_READ
fuer Polling") for the root-cause writeup on the firmware side.

read_active_profile() now sends VersaMCU's new CMD_READ_STATUS (0x06)
and reads back a single EVT_STATUS (0x86) packet instead of driving
the chunked dump protocol. Requires the corresponding firmware update
(VersaMCU commit "Add lightweight READ_STATUS command..."); older
firmware without it just times out gracefully (last_error stays
"timeout", no crash).

desktop_viewer.py's SERIAL_POLL_S/SERIAL_IDLE_S already sit back at
their original 1.5s/3.0s (temporarily raised to 8s as a stopgap before
the firmware fix landed) since the expensive dump is gone now.

Verified end-to-end against a freshly flashed board: correct profile
returned, no more visible LED stutter with Live-Sync on.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

versapad_serial.py

@@ -37,6 +37,7 @@ CONFIG_SIZE = 740
 MACRO_SIZE = 512
 ACTIVE_PROFILE_OFFSET = 7
 
+CMD_READ_STATUS = 0x06
 CMD_CONFIG_BEGIN = 0x10
 CMD_CONFIG_DATA = 0x11
 CMD_CONFIG_COMMIT = 0x12
@@ -46,6 +47,7 @@ CMD_MACRO_DATA = 0x21
 CMD_MACRO_COMMIT = 0x22
 CMD_MACRO_READ = 0x23
 
+EVT_STATUS = 0x86
 EVT_CONFIG_ACK = 0x90
 EVT_CONFIG_NACK = 0x91
 EVT_CONFIG_BEGIN = 0x92
@@ -187,16 +189,39 @@ class VersaPadLink:
 
     # ── Oeffentliche API ────────────────────────────────────────
 
-    def read_active_profile(self):
-        """0-2 bei Erfolg, None bei Timeout/Fehler/kein Board."""
-        buf = self._read_dump(CMD_CONFIG_READ, EVT_CONFIG_BEGIN, EVT_CONFIG_DATA, EVT_CONFIG_END, CONFIG_SIZE)
-        if buf is None:
+    def read_active_profile(self, deadline_s=1.0):
+        """0-2 bei Erfolg, None bei Timeout/Fehler/kein Board.
+
+        Nutzt CMD_READ_STATUS (1 Antwortpaket) statt eines vollen CONFIG_READ-
+        Dumps (124 Pakete) -- der volle Dump blockiert die Firmware lange genug,
+        dass laufende LED-Pulse-Animationen beim Live-Sync-Polling sichtbar
+        stottern (siehe VersaMCU doc/07_serial_protocol.md, "READ_STATUS vs.
+        CONFIG_READ fuer Polling"). Für ältere Firmware ohne CMD_READ_STATUS
+        faellt das Board auf keine Antwort zurueck -> Timeout, kein Absturz."""
+        if not self._ensure_open():
             return None
-        profile = buf[ACTIVE_PROFILE_OFFSET]
-        if profile not in (0, 1, 2):
+        try:
+            self.ser.reset_input_buffer()
+            self.ser.write(bytes([CMD_READ_STATUS, 0, 0, 0, 0, 0, 0, 0]))
+
+            deadline = time.time() + deadline_s
+            while time.time() < deadline:
+                raw = self.ser.read(PACKET_SIZE)
+                if len(raw) < PACKET_SIZE:
+                    continue
+                if raw[0] == EVT_STATUS:
+                    profile = raw[1]
+                    if profile not in (0, 1, 2):
+                        self.last_error = "timeout"
+                        return None
+                    self.last_error = None
+                    return profile
             self.last_error = "timeout"
             return None
-        return profile
+        except serial.SerialException:
+            self.close()
+            self.last_error = "busy"
+            return None
 
     def read_full_config(self):
         """740B Rohdaten (alle 3 Profile) oder None."""