fix(terminal): prevent cursor movement on double-click selection (manaflow-ai#1709)

Double-clicking to select text in the terminal was causing unwanted cursor
movement because the mouse position was being updated on both the first and
second clicks. This disrupted the selection gesture and caused the cursor to
jump to a different position than intended.

Fix by only updating the mouse position on the first click (clickCount == 1),
allowing the terminal's selection logic to handle multi-click gestures without
cursor interference.

Fixes manaflow-ai#1698

Co-authored-by: BillionClaw <267901332+BillionClaw@users.noreply.github.com>

Author: BillionClaw

Sources/GhosttyTerminalView.swift

@@ -5868,7 +5868,11 @@ class GhosttyNSView: NSView, NSUserInterfaceValidations {
         }
         guard let surface = surface else { return }
         let point = convert(event.locationInWindow, from: nil)
-        ghostty_surface_mouse_pos(surface, point.x, bounds.height - point.y, modsFromEvent(event))
+        // Only update mouse position on the first click to prevent unwanted cursor
+        // movement during double-click selection (issue #1698)
+        if event.clickCount == 1 {
+            ghostty_surface_mouse_pos(surface, point.x, bounds.height - point.y, modsFromEvent(event))
+        }
         _ = ghostty_surface_mouse_button(surface, GHOSTTY_MOUSE_PRESS, GHOSTTY_MOUSE_LEFT, modsFromEvent(event))
     }