fix: align Desktop.click() default to single-click (clicks=1)

The Click-Tool definition exposed clicks=1 but Desktop.click() defaulted
to clicks=2, causing unexpected double-clicks when callers relied on the
default. Aligns the service layer to match the tool's documented behavior.

Resolves the click-default mismatch from PR #282; null-guard fixes for
resize_app/switch_app were already covered by the prior refactor.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Jeomon

src/windows_mcp/desktop/service.py

@@ -627,7 +627,7 @@ def get_coordinates_from_labels(self, labels: list[int]) -> list[tuple[int, int]
             results.append((element_node.center.x, element_node.center.y))
         return results
 
-    def click(self, loc: tuple[int, int] | list[int], button: str = "left", clicks: int = 2):
+    def click(self, loc: tuple[int, int] | list[int], button: str = "left", clicks: int = 1):
         if isinstance(loc, list):
             x, y = loc[0], loc[1]
         else: