Switch the motors off when the designs are done or stopped

After the last design (or a Stop), the player sends $SLP (GRBL and FluidNC
sleep), so the motors stop holding and the table is quiet. The page shows
"Motors off"; the next design wakes the controller (reset + unlock) and homes
first, since the arm can be moved by hand while the motors are off. The jog
panel wakes it too. Setting: motion.motors_off_when_done (default true).

Checked on the real Uno: Idle -> $SLP -> Sleep -> reset -> Alarm -> $X -> Idle.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

software/sandtable/ui.py

@@ -212,7 +212,8 @@ class Panel:
 
     def status(self):
         st = self.c.status
-        return {'state': 'Disconnected' if not self.connected else self.busy or (st.state + (':' + st.sub if st.sub else '')),
+        state = 'Motors off' if st.state == 'Sleep' else st.state + (':' + st.sub if st.sub else '')
+        return {'state': 'Disconnected' if not self.connected else self.busy or state,
                 'connected': self.connected,
                 'theta': st.wpos[0], 'rho': st.wpos[1], 'switch': 'Y' in st.pins, 'pins': st.pins,
                 'homed': self.homed, 'steps': self.steps, 'error': self.error}
@@ -224,6 +225,9 @@ class Panel:
         feed = 1200 if axis == 'X' else 600       # 20 deg/s, 10 mm/s
         with self.lock:
             st = self.c.query()
+            if st.state == 'Sleep':                 # motors switched off after a design: wake them
+                self.c.unlock()
+                st = self.c.query()
             if st.state == 'Alarm':
                 return False, 'alarm: press Unlock first'
             inward = axis == 'Y' and d < 0
@@ -263,6 +267,7 @@ class Panel:
 
     def unlock(self):
         with self.lock:
+            self.c.unlock()                         # also wakes the motors after a design
             self.c.command('$X')
         return True, 'unlocked'