🔧 Replace Vite/Vitest with TypeScript 7 and node --test

- Use tsc 7 for build (vite no longer needed for a Node library)
- Use node --test with --experimental-strip-types for tests (vitest dropped)
- Use c8 for coverage instead of vitest's built-in coverage
- Add tsconfig.build.json separating typecheck from emit config
- Drop DOM lib, add strict noUncheckedIndexedAccess/noImplicitOverride
- Pin engines.node to >=22.6 (required for --experimental-strip-types)
- Update CI to Node 24 LTS (unflagged strip-types)
- Add @types/node for node:test / node:assert types

tsconfig.json

@@ -1,20 +1,11 @@
 {
     "compilerOptions": {
-        "target": "ES2022",
-        "useDefineForClassFields": true,
-        "module": "ESNext",
-        "lib": [
-            "ES2022",
-            "DOM"
-        ],
-        "skipLibCheck": true,
-        /* Bundler mode */
-        "moduleResolution": "Node",
-        "allowImportingTsExtensions": true,
-        "isolatedModules": true,
+        "target": "es2024",
+        "module": "nodenext",
+        "moduleResolution": "nodenext",
         "moduleDetection": "force",
-        "noEmit": false,
-        /* Linting */
+        "lib": ["es2024"],
+        "skipLibCheck": true,
         "strict": true,
         "noImplicitAny": true,
         "noImplicitThis": true,
@@ -25,22 +16,22 @@
         "strictPropertyInitialization": true,
         "noImplicitReturns": true,
         "noFallthroughCasesInSwitch": true,
+        "noUncheckedIndexedAccess": true,
+        "noImplicitOverride": true,
         "forceConsistentCasingInFileNames": true,
         "noUnusedLocals": true,
         "noUnusedParameters": true,
-        "noUncheckedSideEffectImports": true,
+        "isolatedModules": true,
+        "verbatimModuleSyntax": true,
         "declaration": true,
         "declarationMap": true,
+        "sourceMap": true,
         "outDir": "dist",
         "esModuleInterop": true,
         "allowSyntheticDefaultImports": true,
         "resolveJsonModule": true,
         "composite": false,
-        "types": [
-            "vitest"
-        ]
+        "types": ["node"]
     },
-    "include": [
-        "src"
-    ]
-}
+    "include": ["src"]
+}