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/components/graph/GraphCanvas.vue

@@ -113,7 +113,6 @@ import { useWorkflowStore } from '@/platform/workflow/management/stores/workflow
 import { useWorkflowAutoSave } from '@/platform/workflow/persistence/composables/useWorkflowAutoSave'
 import { useWorkflowPersistence } from '@/platform/workflow/persistence/composables/useWorkflowPersistence'
 import { useCanvasStore } from '@/renderer/core/canvas/canvasStore'
-import { attachSlotLinkPreviewRenderer } from '@/renderer/core/canvas/links/slotLinkPreviewRenderer'
 import { useCanvasInteractions } from '@/renderer/core/canvas/useCanvasInteractions'
 import TransformPane from '@/renderer/core/layout/transform/TransformPane.vue'
 import MiniMap from '@/renderer/extensions/minimap/MiniMap.vue'
@@ -401,7 +400,6 @@ onMounted(async () => {
 
   // @ts-expect-error fixme ts strict error
   await comfyApp.setup(canvasRef.value)
-  attachSlotLinkPreviewRenderer(comfyApp.canvas)
   canvasStore.canvas = comfyApp.canvas
   canvasStore.canvas.render_canvas_border = false
   workspaceStore.spinner = false