docs: update MCP api resource with canvas.width()/height()

app/src/main/java/com/nonvioce/ijs/McpServer.java

@@ -928,7 +928,7 @@ public class McpServer extends NanoHTTPD {
             symja.put("binomial", "(n,k) - binomial coefficient");
             symja.put("matrix", "{det,inverse,transpose,eigenvalues,rank}");
             api.put("IJS.Symja", symja);
-            api.put("IJS.canvas", "create(w,h), getContext(), getSize(), clear(), fill(color), size(w,h), loop(cb), stop()");
+            api.put("IJS.canvas", "create(w?,h?), getContext(), getSize(), width(), height(), clear(), fill(color), size(w,h), loop(cb), stop() — create() without args auto-fills fullscreen panel");
             api.put("IJS.input", "onTouchStart(cb), onTouchMove(cb), onTouchEnd(cb)");
             api.put("IJS.io", "read(filename), write(filename,content), list(), delete(filename)");
             api.put("IJS.audio", "beep(freq,dur,type), playNote(note,oct,dur), playMelody(melody,tempo)");