fix(web): map Node-only specifiers to false via browser field

Browser bundlers (esbuild, webpack, vite, rollup) statically discover the
`await import("fs/promises")` and `await import("module")` calls in the
shipped ESM bundle and try to resolve them, even though both sit in
Node-only branches that never execute in a browser.

Adding a top-level `browser` field tells bundlers to substitute empty
stubs for these specifiers when targeting the browser. The runtime gates
(`globalThis.process?.versions.node` and `ENVIRONMENT_IS_NODE`) already
prevent the stubs from ever being invoked.

Fixes #5545.

lib/binding_web/package.json

@@ -43,6 +43,11 @@
     },
     "./debug/web-tree-sitter.wasm": "./debug/web-tree-sitter.wasm"
   },
+  "browser": {
+    "fs": false,
+    "fs/promises": false,
+    "module": false
+  },
   "types": "web-tree-sitter.d.ts",
   "keywords": [
     "incremental",