Call it a node pack, not a plugin

"Plugin" is not ComfyUI's vocabulary. What Manager installs into custom_nodes/
is a custom node pack, and what the Registry publishes is a "node" — so to
someone browsing the Registry, "plugin" reads slightly off-ecosystem, like
calling a VS Code extension an add-on. The README is the listing page, so the
wording is user-facing.

Replaces the eight occurrences with "node pack", "the nodes", or "this pack" as
each sentence reads best. "Extension" stays reserved for its narrow ComfyUI
meaning: the frontend JS registered via app.registerExtension, which is
web/styleref.js and nothing else.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

styleref_api.py

@@ -31,7 +31,7 @@ DEFAULT_TIMEOUT_S = 30
 
 
 def api_base() -> str:
-    """Env override exists so the plugin can be pointed at a local dev server."""
+    """Env override exists so the nodes can be pointed at a local dev server."""
     return (os.environ.get("STYLEREF_API") or "").strip() or DEFAULT_API_BASE