Add extracted source directory and README navigation

extracted-source/vendor/modifiers-napi-src/index.ts

@@ -0,0 +1,67 @@
+import { createRequire } from 'module'
+import { fileURLToPath } from 'url'
+import { dirname, join } from 'path'
+
+type ModifiersNapi = {
+  getModifiers(): string[]
+  isModifierPressed(modifier: string): boolean
+}
+
+let cachedModule: ModifiersNapi | null = null
+
+function loadModule(): ModifiersNapi | null {
+  if (cachedModule) {
+    return cachedModule
+  }
+
+  // Only works on macOS
+  if (process.platform !== 'darwin') {
+    return null
+  }
+
+  try {
+    if (process.env.MODIFIERS_NODE_PATH) {
+      // Bundled mode - use the env var path
+      // eslint-disable-next-line @typescript-eslint/no-require-imports
+      cachedModule = require(process.env.MODIFIERS_NODE_PATH) as ModifiersNapi
+    } else {
+      // Dev mode - load from vendor directory
+      const modulePath = join(
+        dirname(fileURLToPath(import.meta.url)),
+        '..',
+        'modifiers-napi',
+        `${process.arch}-darwin`,
+        'modifiers.node',
+      )
+      cachedModule = createRequire(import.meta.url)(modulePath) as ModifiersNapi
+    }
+    return cachedModule
+  } catch {
+    return null
+  }
+}
+
+export function getModifiers(): string[] {
+  const mod = loadModule()
+  if (!mod) {
+    return []
+  }
+  return mod.getModifiers()
+}
+
+export function isModifierPressed(modifier: string): boolean {
+  const mod = loadModule()
+  if (!mod) {
+    return false
+  }
+  return mod.isModifierPressed(modifier)
+}
+
+/**
+ * Pre-warm the native module by loading it in advance.
+ * Call this early (e.g., at startup) to avoid delay on first use.
+ */
+export function prewarm(): void {
+  // Just call loadModule to cache it
+  loadModule()
+}