fix publish: generate platform packages manually, add optionalDependencies

Skip napi prepublish/artifacts commands that require GitHub API auth.
Instead, create platform package.json files and copy binaries directly.
Add optionalDependencies to main package so npm/bun auto-selects the
right binary.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

napi/package.json

@@ -4,6 +4,10 @@
   "main": "index.js",
   "types": "index.d.ts",
   "license": "MIT",
+  "files": [
+    "index.js",
+    "index.d.ts"
+  ],
   "repository": {
     "type": "git",
     "url": "https://github.com/firecrawl/pdf-inspector"
@@ -22,11 +26,13 @@
       "name": "@firecrawl/pdf-inspector-js"
     }
   },
+  "optionalDependencies": {
+    "@firecrawl/pdf-inspector-js-linux-x64-gnu": "0.2.0",
+    "@firecrawl/pdf-inspector-js-darwin-arm64": "0.2.0"
+  },
   "scripts": {
     "build": "napi build --platform --release",
-    "build:debug": "napi build --platform",
-    "prepublishOnly": "napi prepublish -t npm",
-    "artifacts": "napi artifacts"
+    "build:debug": "napi build --platform"
   },
   "devDependencies": {
     "@napi-rs/cli": "^3.4.1"