[feat] Node replacement UI (#8604)

## Summary
Add node replacement UI to the missing nodes dialog. Users can select
and replace deprecated/missing nodes with compatible alternatives
directly from the dialog.

## Changes
- Classify missing nodes into **Replaceable** (quick fix) and **Install
Required** sections
- Add select-all checkbox + per-node checkboxes for batch replacement
- `useNodeReplacement` composable handles in-place node replacement on
the graph:
  - Simple replacement (configure+copy) for nodes without mapping
  - Input/output connection remapping for nodes with mapping
  - Widget value transfer via `old_widget_ids`
  - Dot-notation input handling for Autogrow/DynamicCombo
  - Undo/redo support via `changeTracker` (try/finally)
  - Title and properties preservation
- Footer UX: "Skip for Now" button when all nodes are replaceable (cloud
+ OSS)
- Auto-close dialog when all replaceable nodes are replaced and no
non-replaceable remain
- Settings navigation link from "Don't show again" checkbox
- 505-line unit test suite for `useNodeReplacement`

## Review Focus
- `useNodeReplacement.ts` — core graph manipulation logic
- `MissingNodesContent.vue` — checkbox selection state management
- `MissingNodesFooter.vue` — conditional button rendering (cloud vs OSS
vs all-replaceable)


[screen-capture.webm](https://github.com/user-attachments/assets/7dae891c-926c-4f26-987f-9637c4a2ca16)

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8604-feat-Node-replacement-UI-2fd6d73d36508148a371dabb8f4115af)
by [Unito](https://www.unito.io)

---------

Co-authored-by: github-actions <github-actions@github.com>

src/locales/en/main.json

@@ -2903,6 +2903,25 @@
       "replacementInstruction": "Install these nodes to run this workflow, or replace them with installed alternatives. Missing nodes are highlighted in red on the canvas."
     }
   },
+  "nodeReplacement": {
+    "quickFixAvailable": "Quick Fix Available",
+    "installationRequired": "Installation Required",
+    "compatibleAlternatives": "Compatible Alternatives",
+    "replaceable": "Replaceable",
+    "replaced": "Replaced",
+    "notReplaceable": "Install Required",
+    "selectAll": "Select All",
+    "replaceSelected": "Replace Selected ({count})",
+    "replacedNode": "Replaced node: {nodeType}",
+    "replacedAllNodes": "Replaced {count} node type(s)",
+    "replaceFailed": "Failed to replace nodes",
+    "instructionMessage": "You must install these nodes or replace them with installed alternatives to run the workflow. Missing nodes are highlighted in {red} on the canvas. Some nodes cannot be swapped and must be installed via Node Manager.",
+    "redHighlight": "red",
+    "openNodeManager": "Open Node Manager",
+    "skipForNow": "Skip for Now",
+    "installMissingNodes": "Install Missing Nodes",
+    "replaceWarning": "This will permanently modify the workflow. Save a copy first if unsure."
+  },
   "rightSidePanel": {
     "togglePanel": "Toggle properties panel",
     "noSelection": "Select a node to see its properties and info.",