feat(canvas): import DWG/DXF CAD drawings as canvas assets

Accept DWG and DXF files (up to 24 MB) through the canvas asset picker and
drag-and-drop. Conversion runs locally in a browser worker via acad-ts,
uploads a sanitized derived SVG, and leaves the source file untouched. DXF
covers ASCII and binary drawings; DWG covers AutoCAD R14 through 2018.

Rename the image-only upload input/handler to a generic canvas asset flow,
add vector-image node detection, tag imported SVGs as vector-image nodes,
localize CAD import status/error messages, and switch the Next build to the
webpack compiler so the worker bundles correctly. Add a node --test suite
covering CAD conversion and vector image helpers.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/pnpm-lock.yaml

@@ -5,6 +5,9 @@ settings:
   excludeLinksFromLockfile: false
 
 dependencies:
+  '@node-projects/acad-ts':
+    specifier: 2.3.0
+    version: 2.3.0
   '@radix-ui/react-context-menu':
     specifier: ^2.3.2
     version: 2.3.2(@types/react-dom@19.2.3)(@types/react@19.2.17)(react-dom@19.2.7)(react@19.2.7)
@@ -439,6 +442,10 @@ packages:
     dev: false
     optional: true
 
+  /@node-projects/acad-ts@2.3.0:
+    resolution: {integrity: sha512-qeEHH6apsBZPWVXx489ju0Qln/YyhIffREic+alksgj5F4KsaD+GAE96si1P8RNFbJbZQOSG85bo0749MpzCDA==}
+    dev: false
+
   /@oxc-project/types@0.138.0:
     resolution: {integrity: sha512-1a7ZKmrRTCoN1XMZ4L0PyyqrMnrNlLyPuOkdSX2MZg7IiIGRUyurNhAm73ptDOraoBcIordsIGKNPKUzy3ZmfA==}
     dev: true