Add TypeScript build config for .d.ts declaration output

Set up tsconfig.json (declaration: true, DOM lib), package.json with
main/types/files pointing at dist, and .gitignore for node_modules/dist
so the library can be consumed with type declarations.

package-lock.json

@@ -0,0 +1,29 @@
+{
+  "name": "abstract-ts-table",
+  "version": "1.0.0",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {
+    "": {
+      "name": "abstract-ts-table",
+      "version": "1.0.0",
+      "license": "MIT",
+      "devDependencies": {
+        "typescript": "^6.0.3"
+      }
+    },
+    "node_modules/typescript": {
+      "version": "6.0.3",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-6.0.3.tgz",
+      "integrity": "sha512-y2TvuxSZPDyQakkFRPZHKFm+KKVqIisdg9/CZwm9ftvKXLP8NRWj38/ODjNbr43SsoXqNuAisEf1GdCxqWcdBw==",
+      "dev": true,
+      "bin": {
+        "tsc": "bin/tsc",
+        "tsserver": "bin/tsserver"
+      },
+      "engines": {
+        "node": ">=14.17"
+      }
+    }
+  }
+}