plugins: node_modules is not a broken plugin

The shared install target for plugin npm packages lives in plugins/ because bun resolves node_modules
up the tree. Discovery then found it, failed to read a manifest, and reported it as broken on every
call — a warning nobody can act on, and a denominator that made the marketplace sync report 15/16.

Mine, from the npm-dependencies work.

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

src/servers/plugins/discover.ts

@@ -141,6 +141,11 @@ export async function discoverPlugins(root: string = PLUGINS_DIR): Promise<Disco
   for (const entry of readdirSync(root)) {
     // `_`-prefixed directories are scratch space, and dotfiles are not plugins.
     if (entry.startsWith('.') || entry.startsWith('_')) continue;
+    // Nor is the shared install target for plugin npm packages, which lives here because bun resolves
+    // node_modules up the tree — see npm-deps.ts. It was reported as a broken plugin on every discovery
+    // ("node_modules: no manifest.ts"), which is a warning nobody can act on and a denominator that
+    // makes the marketplace sync say 15/16.
+    if (entry === 'node_modules') continue;
     const dir = join(root, entry);
     try {
       if (!statSync(dir).isDirectory()) continue;