feat: game pause/speed control API with AI pause protocol

- POST /api/action/pause - pause game (AI must call before operations)
- POST /api/action/unpause - resume game at desired speed
- POST /api/action/speed - set game speed (1x/2x/3x)
- Game state now includes isPaused and gameSpeed
- AI pause protocol documented in SKILL.md: pause before every operation
- Introduces cell.isDiggable flag that filters neutronium properly
- pause/unpause/speed CLI commands added to oni_api.py

tools/oni_api.py

@@ -474,6 +474,30 @@ def cmd_priority_type(args):
     })
     _print_feedback(result)
 
+def cmd_pause(args):
+    """Pause the game. Usage: pause [reason]"""
+    reason = ' '.join(args) if args else 'AI operation in progress'
+    result = api_post('/api/action/pause', {} if not args else {"reason": reason})
+    _print_feedback(result)
+
+def cmd_unpause(args):
+    """Unpause the game. Usage: unpause [speed]"""
+    speed = int(args[0]) if args else 1
+    result = api_post('/api/action/unpause', {"speed": speed})
+    _print_feedback(result)
+
+def cmd_speed(args):
+    """Set game speed. Usage: speed <1|2|3>"""
+    if not args:
+        print("Usage: speed <1|2|3>")
+        return
+    speed = int(args[0])
+    if speed < 1 or speed > 3:
+        print("Speed must be 1, 2, or 3")
+        return
+    result = api_post('/api/action/speed', {"speed": speed})
+    _print_feedback(result)
+
 def _print_feedback(result):
     """Pretty-print action feedback."""
     if result.get('success'):
@@ -584,6 +608,9 @@ COMMANDS = {
     'batch': cmd_batch,
     'priority_global': cmd_priority_global,
     'priority_type': cmd_priority_type,
+    'pause': cmd_pause,
+    'unpause': cmd_unpause,
+    'speed': cmd_speed,
 }
 
 if __name__ == '__main__':
@@ -631,6 +658,11 @@ if __name__ == '__main__':
         print("  mop <x> <y>              Mop liquid")
         print("  harvest <x> <y>          Harvest plant")
         print("")
+        print("=== Game Speed Control ===")
+        print("  pause [reason]           Pause the game (AI should always pause before ops)")
+        print("  unpause [speed]          Unpause the game at 1x/2x/3x speed")
+        print("  speed <1|2|3>            Set game speed while running")
+        print("")
         print("=== Batch / Priority (Advanced) ===")
         print("  batch <json_file>        Execute batch plan")
         print("  priority_global <t> <p>  Set global default priority")