fix(tasks): treat blank JSON filters as absent (#103981)

* fix(tasks): normalize blank JSON filters

* fix(tasks): reuse optional string normalization

* fix(tasks): share blank filter normalization

---------

Co-authored-by: Vincent Koc <vincentkoc@ieee.org>

src/cli/program/routes.test.ts

@@ -520,6 +520,24 @@ describe("program routes", () => {
       { json: true, runtime: "cron", status: undefined },
       defaultRuntime,
     );
+
+    await expect(
+      listRoute.run([
+        "node",
+        "openclaw",
+        "tasks",
+        "list",
+        "--json",
+        "--runtime",
+        "   ",
+        "--status",
+        "\t",
+      ]),
+    ).resolves.toBe(true);
+    expect(tasksListJsonCommandMock).toHaveBeenLastCalledWith(
+      { json: true, runtime: "   ", status: "\t" },
+      defaultRuntime,
+    );
   });
 
   it("routes parent task filter values that command-path discovery sees as positionals", async () => {
@@ -584,6 +602,24 @@ describe("program routes", () => {
       { json: true, severity: "error", code: "stale_running", limit: 5 },
       defaultRuntime,
     );
+
+    await expect(
+      route.run([
+        "node",
+        "openclaw",
+        "tasks",
+        "audit",
+        "--json",
+        "--severity",
+        "  ",
+        "--code",
+        "\t",
+      ]),
+    ).resolves.toBe(true);
+    expect(tasksAuditJsonCommandMock).toHaveBeenLastCalledWith(
+      { json: true, severity: "  ", code: "\t", limit: undefined },
+      defaultRuntime,
+    );
   });
 
   it("returns false for task JSON routes when option values are missing or unknown", async () => {