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/types/config.ts

@@ -348,6 +348,74 @@ export interface ActionConfig {
   definition_vars: Record<string, string>;
   /** [Init] section key-value pairs. */
   init_vars: Record<string, string>;
+  /**
+   * True when this action is referenced by at least one currently running jail.
+   */
+  active: boolean;
+  /**
+   * Names of currently enabled jails that reference this action.
+   * Empty when active is false.
+   */
+  used_by_jails: string[];
+  /** Absolute path to the .conf source file. Empty string when not computed. */
+  source_file: string;
+  /** True when a .local override file exists alongside the base .conf. */
+  has_local_override: boolean;
+}
+
+/**
+ * Response for GET /api/config/actions.
+ * Lists all discovered actions with active/inactive status.
+ */
+export interface ActionListResponse {
+  actions: ActionConfig[];
+  total: number;
+}
+
+/**
+ * Payload for ``PUT /api/config/actions/{name}``.
+ *
+ * Only editable lifecycle fields are accepted.
+ * Fields set to ``null`` or omitted leave the existing value unchanged.
+ */
+export interface ActionUpdateRequest {
+  actionstart?: string | null;
+  actionstop?: string | null;
+  actioncheck?: string | null;
+  actionban?: string | null;
+  actionunban?: string | null;
+  actionflush?: string | null;
+  definition_vars?: Record<string, string> | null;
+  init_vars?: Record<string, string> | null;
+}
+
+/**
+ * Payload for ``POST /api/config/actions``.
+ *
+ * Creates a new user-defined action at ``action.d/{name}.local``.
+ */
+export interface ActionCreateRequest {
+  /** Base name without extension (e.g. ``my-action``). */
+  name: string;
+  actionstart?: string | null;
+  actionstop?: string | null;
+  actioncheck?: string | null;
+  actionban?: string | null;
+  actionunban?: string | null;
+  actionflush?: string | null;
+  definition_vars?: Record<string, string> | null;
+  init_vars?: Record<string, string> | null;
+}
+
+/**
+ * Payload for ``POST /api/config/jails/{jail_name}/action``.
+ *
+ * Adds an action to a jail's action list.
+ */
+export interface AssignActionRequest {
+  action_name: string;
+  /** Optional parameters for the action (e.g. ``{ port: "ssh" }``). */
+  params?: Record<string, string>;
 }
 
 /**