Implement drop-on-canvas + linkconnectoradapter consolidation (#5898)

Implements droponcanvas functionality and a linkconnectoradapter
refactor.

- Drop on canvas (Shift and default) integrated via LinkConnector
‘dropped-on-canvas’ with proper CanvasPointerEvent.
- LinkConnector adapter: now wraps the live canvas linkConnector (no
duplicate state); added dropOnCanvas() helper.
- Tests: Playwright scenarios for Shift-drop context menu/searchbox,
pinned endpoint, type prefilter, and post-selection auto-connect
(browser_tests/tests/vueNodes/interactions/links/linkInteraction.spec.ts).

There are some followup PRs that will fix/refactor some more noncritical
things, like the terrible slotid, the number/string nodeid confusion,
etc.

https://github.com/Comfy-Org/ComfyUI_frontend/pull/5780 (snapping) <--
https://github.com/Comfy-Org/ComfyUI_frontend/pull/5898 (drop on canvas
+ linkconnectoradapter refactor) <--
https://github.com/Comfy-Org/ComfyUI_frontend/pull/5903 (fix reroute
snapping)

---------

Co-authored-by: github-actions <github-actions@github.com>
Co-authored-by: Christian Byrne <cbyrne@comfy.org>
Co-authored-by: GitHub Action <action@github.com>

src/lib/litegraph/src/LGraphNode.ts

@@ -3326,11 +3326,14 @@ export class LGraphNode
    * Gets the position of an output slot, in graph co-ordinates.
    *
    * This method is preferred over the legacy {@link getConnectionPos} method.
-   * @param slot Output slot index
+   * @param outputSlotIndex Output slot index
    * @returns Position of the output slot
    */
-  getOutputPos(slot: number): Point {
-    return calculateOutputSlotPos(this.#getSlotPositionContext(), slot)
+  getOutputPos(outputSlotIndex: number): Point {
+    return calculateOutputSlotPos(
+      this.#getSlotPositionContext(),
+      outputSlotIndex
+    )
   }
 
   /** @inheritdoc */