feat: prepare project for cozy-ui migration (#157)

* feat: prepare project for cozy-ui migration

Build Configuration
- Add Stylus support via @rsbuild/plugin-stylus
- Add SVGR support via @rsbuild/plugin-svgr
- Update rsbuild.config.ts with custom configuration
- Add historyApiFallback for SPA routing

ESLint Configuration
- Create .eslintrc.json with react-app configuration
- Remove eslintConfig from package.json

CSS to Stylus Migration
Convert all 5 CSS files to Stylus (.styl) format:
  - src/App.css to src/App.styl
  - src/index.css to src/index.styl
  - src/components/Calendar/Calendar.css to src/components/Calendar/Calendar.styl
  - src/components/Calendar/CustomCalendar.css to src/components/Calendar/CustomCalendar.styl
  - src/components/Menubar/Menubar.css to src/components/Menubar/Menubar.styl
- Update all imports from .css to .styl
- Preserve all styling rules and values

MUI Styling Cleanup
- Replace all MUI sx props with standard style props across 15+ components
- Convert MUI spacing units (mr: 2 to marginRight: 16px)
- Convert MUI shorthand props (p: 2 to padding: 16px, mb: 1 to marginBottom: 8px)
- Remove MUI-specific syntax (&.Mui-checked selectors)
- Maintain exact visual appearance

FullCalendar Fixes
- Comment out problematic CSS rule in CustomCalendar.styl
- Fix display issues with timegrid slot labels

Files Modified
- Config: rsbuild.config.ts, .eslintrc.json, package.json
- Styling: 5 CSS to Stylus conversions, 15+ component sx to style updates
- Components: All components using MUI sx props updated

Development Workflow
- Continue using existing development commands
- Stylus files are now the source of truth for styling
- MUI components work with standard style props
- ESLint uses familiar react-app rules

Dependencies Added
- @rsbuild/plugin-stylus
- @rsbuild/plugin-svgr

package.json

@@ -36,15 +36,9 @@
     "build": "rsbuild build",
     "preview": "rsbuild preview",
     "test": "jest",
-    "lint": "eslint src",
+    "lint": "eslint src --ext .js,.jsx,.ts,.tsx",
     "jest-preview": "jest-preview"
   },
-  "eslintConfig": {
-    "extends": [
-      "react-app",
-      "react-app/jest"
-    ]
-  },
   "browserslist": {
     "production": [
       ">0.2%",
@@ -61,23 +55,35 @@
     "node": "24.x"
   },
   "devDependencies": {
+    "@babel/eslint-parser": "^7.28.4",
     "@babel/preset-env": "^7.28.0",
     "@babel/preset-react": "^7.27.1",
     "@rsbuild/core": "^1.5.2",
     "@rsbuild/plugin-react": "^1.3.3",
+    "@rsbuild/plugin-stylus": "^1.2.0",
     "@rsbuild/plugin-svgr": "^1.2.0",
     "@testing-library/dom": "^10.4.0",
     "@testing-library/jest-dom": "^6.6.3",
     "@testing-library/react": "^16.3.0",
     "@testing-library/user-event": "^13.5.0",
     "@types/jest": "^30.0.0",
+    "@typescript-eslint/eslint-plugin": "^8.44.1",
+    "@typescript-eslint/parser": "^8.44.1",
     "babel-jest": "^30.0.4",
     "eslint": "^8.57.1",
+    "eslint-config-prettier": "^10.1.8",
     "eslint-config-react-app": "^7.0.1",
+    "eslint-plugin-import": "^2.32.0",
+    "eslint-plugin-jest": "^29.0.1",
+    "eslint-plugin-promise": "^7.2.1",
+    "eslint-plugin-react": "^7.37.5",
+    "eslint-plugin-react-hooks": "^5.2.0",
+    "history": "^5.3.0",
     "i18next-resources-for-ts": "1.4.0",
     "jest": "^30.0.4",
     "jest-environment-jsdom": "^30.0.4",
     "jest-preview": "^0.3.1",
+    "prettier": "^3.6.2",
     "ts-jest": "^29.4.0",
     "typescript": "^4.9.5"
   }