fix: use descriptor.type instead of isUnified for source dir detection

The isUnified field was never set on plugin descriptors. Singlerepo plugins
have content directories in package root, monorepo plugins have them in
.opencode/ subdirectory. Now correctly uses descriptor.type to determine
the source directory path.

Author: wagnert

lib/linker.js

@@ -68,23 +68,23 @@ export function normalizeContentType(type) {
 /**
  * Gets source directory for a plugin based on type.
  * 
- * For unified plugins: content is in package root (agent/, command/, etc.)
- * For legacy plugins: content is in .opencode/ subdirectory
+ * For singlerepo plugins: content is in package root (agents/, commands/, etc.)
+ * For monorepo plugins: content is in .opencode/ subdirectory
  * 
  * @param {PluginDescriptor} descriptor - Plugin descriptor
- * @param {string} type - Content type (agent, command, skill, etc.)
+ * @param {string} type - Content type (agents, commands, skills, etc.)
  * @returns {string|null} Source directory path or null if not exists
  */
 export function getSourceDir(descriptor, type) {
   if (!descriptor.contentTypes.includes(type)) {
     return null;
   }
 
-  if (descriptor.isUnified) {
-    // Unified plugin: content in package root
+  if (descriptor.type === 'singlerepo') {
+    // Singlerepo plugin: content in package root
     return path.join(descriptor.rootDir, type);
   } else {
-    // Legacy plugin: content in .opencode/ subdirectory
+    // Monorepo plugin: content in .opencode/ subdirectory
     return path.join(descriptor.rootDir, '.opencode', type);
   }
 }