semantic markup update

frontend/src/components/tools/MapperTool.svelte

@@ -28,6 +28,8 @@
 
     // [DEF:fetchData:Function]
     // @PURPOSE: Fetches environments and saved connections.
+    // @PRE: None.
+    // @POST: envs and connections arrays are populated.
     async function fetchData() {
         try {
             const envsRes = await fetch('/api/environments');
@@ -41,6 +43,8 @@
 
     // [DEF:handleRunMapper:Function]
     // @PURPOSE: Triggers the MapperPlugin task.
+    // @PRE: selectedEnv and datasetId are set; source-specific fields are valid.
+    // @POST: Mapper task is started and selectedTask is updated.
     async function handleRunMapper() {
         if (!selectedEnv || !datasetId) {
             addToast('Please fill in required fields', 'warning');