chore: add biome for linting/formatting + CI action for linting in SRC folder

.github/workflows/lint.yml

@@ -0,0 +1,22 @@
+name: Code quality
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  quality:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v5
+        with:
+          persist-credentials: false
+      - name: Setup Biome
+        uses: biomejs/setup-biome@v2
+        with:
+          version: latest
+      - name: Run Biome
+        run: biome ci .

biome.json

@@ -0,0 +1,58 @@
+{
+  "$schema": "https://biomejs.dev/schemas/2.3.12/schema.json",
+  "vcs": {
+    "enabled": true,
+    "clientKind": "git",
+    "useIgnoreFile": true
+  },
+  "files": {
+    "includes": ["src/**/*.ts"]
+  },
+  "formatter": {
+    "enabled": true,
+    "indentStyle": "space"
+  },
+  "linter": {
+    "enabled": true,
+    "rules": {
+      "recommended": true,
+      "style": {
+        "useTemplate": {
+          "level": "warn",
+          "fix": "safe"
+        },
+        "noNonNullAssertion": "off"
+      },
+      "suspicious": {
+        "noExplicitAny": "off",
+        "noGlobalIsNan": {
+          "level": "error",
+          "fix": "safe"
+        }
+      },
+      "correctness": {
+        "noUnusedVariables": {
+          "level": "error",
+          "fix": "safe"
+        },
+        "useParseIntRadix": {
+          "fix": "safe",
+          "level": "error"
+        }
+      }
+    }
+  },
+  "javascript": {
+    "formatter": {
+      "quoteStyle": "double"
+    }
+  },
+  "assist": {
+    "enabled": true,
+    "actions": {
+      "source": {
+        "organizeImports": "on"
+      }
+    }
+  }
+}

package.json

@@ -19,9 +19,12 @@
     "preview": "vite preview",
     "test": "vitest",
     "test:browser": "vitest --config=vitest.browser.config.ts",
-    "test:e2e": "playwright test"
+    "test:e2e": "playwright test",
+    "lint": "biome check --write",
+    "format": "biome format --write"
   },
   "devDependencies": {
+    "@biomejs/biome": "2.3.12",
     "@playwright/test": "^1.57.0",
     "@types/d3": "^7.4.3",
     "@types/delaunator": "^5.0.3",