Remove @mui/material dependency from Petrinaut

The last MUI usage (tooltip) was replaced with Ark UI and native SVG,
so the dependency and its ESLint import restriction are no longer needed.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: kube

libs/@hashintel/petrinaut/eslint.config.js

@@ -43,10 +43,6 @@ export default [
         "error",
         {
           patterns: [
-            {
-              group: ["@mui/material/*"],
-              message: "Please import from @mui/material instead",
-            },
             {
               group: ["@local/*"],
               message:

libs/@hashintel/petrinaut/package.json

@@ -48,7 +48,6 @@
     "@hashintel/refractive": "0.0.2",
     "@mantine/hooks": "8.3.5",
     "@monaco-editor/react": "4.8.0-rc.3",
-    "@mui/material": "5.18.0",
     "d3-array": "3.2.4",
     "d3-scale": "4.0.2",
     "elkjs": "0.11.0",

yarn.lock

@@ -8302,7 +8302,6 @@ __metadata:
     "@local/eslint": "npm:0.0.0-private"
     "@mantine/hooks": "npm:8.3.5"
     "@monaco-editor/react": "npm:4.8.0-rc.3"
-    "@mui/material": "npm:5.18.0"
     "@pandacss/dev": "npm:1.4.3"
     "@sentry/react": "npm:10.22.0"
     "@testing-library/dom": "npm:10.4.0"