fix(agents): set isError: false in host edit post-write recovery

When the upstream edit tool throws after writing (e.g. generateDiffString
fails), the recovery check correctly returns a success result, but the
result object lacked an explicit isError: false field. Explicitly setting
isError: false ensures the framework never surfaces a false 'edit failed'
notification, even when internal error-handling paths preserve unexpected
isError flags from caught exceptions.

Also adds an explicit assertion in the existing recovery test that the
returned result has isError: false.

Fixes #32333 (follow-up)

src/agents/pi-tools.host-edit.ts

@@ -63,6 +63,7 @@ export function wrapHostEditToolWithPostWriteRecovery(
             oldText !== undefined && oldText.length > 0 && content.includes(oldText);
           if (hasNew && !stillHasOld) {
             return {
+              isError: false,
               content: [
                 {
                   type: "text",

src/agents/pi-tools.read.host-edit-recovery.test.ts

@@ -61,6 +61,8 @@ describe("createHostWorkspaceEditTool post-write recovery", () => {
       : [];
     const textBlock = content.find((b) => b?.type === "text" && typeof b.text === "string");
     expect(textBlock?.text).toContain("Successfully replaced text");
+    // isError must be explicitly false so the framework does not surface a false failure notification
+    expect((result as { isError?: unknown }).isError).toBe(false);
   });
 
   it("rethrows when file on disk does not contain newText", async () => {