fix: pass workspace context from API key to tool execution

Brain tools require workspace_id in context for data isolation.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/Mcp/Controllers/McpApiController.php

@@ -222,10 +222,16 @@ class McpApiController extends Controller
             throw new \RuntimeException("Tool not found: {$tool}");
         }
 
+        $context = [];
+
+        if ($apiKey?->workspace_id) {
+            $context['workspace_id'] = $apiKey->workspace_id;
+        }
+
         return $registry->execute(
             name: $tool,
             args: $arguments,
-            context: [],
+            context: $context,
             apiKey: $apiKey,
             validateDependencies: false
         );