fix: Stabilize Open note button hover behavior

Remove transform and box-shadow animations from Open note button that
caused visual "jumping" on hover. Replace with consistent border styling
that maintains stable button dimensions across all states (normal, hover,
active). This aligns the button behavior with other modal buttons.

Author: callumalpass

styles/task-modal.css

@@ -229,13 +229,13 @@
 .tasknotes-plugin .open-note-button:hover {
     background: var(--interactive-accent);
     color: var(--text-on-accent);
-    transform: translateY(-1px);
-    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
+    border: 1px solid var(--interactive-accent);
 }
 
 .tasknotes-plugin .open-note-button:active {
-    transform: translateY(0);
-    box-shadow: 0 1px 4px rgba(0, 0, 0, 0.1);
+    background: var(--interactive-accent);
+    color: var(--text-on-accent);
+    border: 1px solid var(--interactive-accent);
 }
 
 .tasknotes-plugin .button-spacer {