feat: frontend Actions Tab with structured API, assign/create/remove dialogs (Task 3.3)

- ActionsTab rewritten with master/detail layout (mirrors FiltersTab)
- New AssignActionDialog and CreateActionDialog components
- ActionConfig type extended with active, used_by_jails, source_file, has_local_override
- New API functions: fetchActions, fetchAction, updateAction, createAction, deleteAction, assignActionToJail, removeActionFromJail
- useActionConfig updated to use new structured endpoints
- index.ts barrel exports updated

frontend/src/hooks/useActionConfig.ts

@@ -3,7 +3,7 @@
  */
 
 import { useCallback, useEffect, useRef, useState } from "react";
-import { fetchParsedAction, updateParsedAction } from "../api/config";
+import { fetchAction, updateAction } from "../api/config";
 import type { ActionConfig, ActionConfigUpdate } from "../types/config";
 
 export interface UseActionConfigResult {
@@ -37,7 +37,7 @@ export function useActionConfig(name: string): UseActionConfigResult {
     setLoading(true);
     setError(null);
 
-    fetchParsedAction(name)
+    fetchAction(name)
       .then((data) => {
         if (!ctrl.signal.aborted) {
           setConfig(data);
@@ -64,7 +64,7 @@ export function useActionConfig(name: string): UseActionConfigResult {
       setSaving(true);
       setSaveError(null);
       try {
-        await updateParsedAction(name, update);
+        await updateAction(name, update);
         setConfig((prev) =>
           prev
             ? {