chore(benchmarks-misc-fixes): cleaned benchmark task/pid validation

- Added `vim` as an edit variant in benchmark CLI/config and rating script coverage.
- Expanded benchmark execution so `vim` is treated as a mutation tool for retries, stats, and edit intent checks.
- Adjusted `TaskTool` output schema precedence so explicit params override agent frontmatter.
- Fixed `TaskTool` success counting by excluding aborted tasks from success totals.
- Improved validation guidance in `SubmitResultTool`/`TodoWriteTool` for clearer recovery when payloads are missing or invalid.
- Added background command PID regression coverage in `executeBash` to confirm a real, terminateable PID is returned.

packages/coding-agent/test/bash-executor.test.ts

@@ -100,6 +100,25 @@ describe("executeBash", () => {
 		expect(Date.now() - start).toBeLessThan(3000);
 	});
 
+	it("returns a real PID for background external commands", async () => {
+		if (process.platform === "win32") {
+			return;
+		}
+
+		const result = await executeBash("sleep 10 & echo $!", {
+			cwd: tempDir,
+			timeout: 5000,
+		});
+		const pid = Number.parseInt(result.output.trim(), 10);
+		expect(Number.isInteger(pid)).toBe(true);
+		expect(pid).toBeGreaterThan(0);
+		expect(() => process.kill(pid, 0)).not.toThrow();
+		process.kill(pid, "SIGTERM");
+		await Bun.sleep(100);
+		expect(() => process.kill(pid, 0)).toThrow();
+	});
+
+
 	it("times out commands", async () => {
 		if (process.platform === "win32") {
 			return;