fix(coding-agent/task): treated stash cleanup paths literally

Failed stash-pop cleanup now invokes git clean with literal pathspecs for
stash-derived untracked paths. Filenames such as `:(glob)*` are valid POSIX
filenames and valid Git pathspec magic; passing them as ordinary pathspecs with
`-x` could delete unrelated ignored artifacts that were never stashed and are
not recoverable from the preserved stash.

Extend the fallback regression with a literal `:(glob)*` stash file and an
ignored `build.log` that must survive cleanup.

Fixes #4175

packages/coding-agent/src/utils/git.ts

@@ -1635,7 +1635,7 @@ export const stash = {
 			}
 			if (restoredUntracked.length > 0) {
 				try {
-					await clean(cwd, { includeIgnored: true, paths: restoredUntracked });
+					await clean(cwd, { includeIgnored: true, literalPathspecs: true, paths: restoredUntracked });
 				} catch {
 					/* best-effort cleanup — do not mask the primary conflict */
 				}
@@ -1709,9 +1709,18 @@ export async function reset(
 
 export async function clean(
 	cwd: string,
-	options: { ignoredOnly?: boolean; includeIgnored?: boolean; paths?: readonly string[]; signal?: AbortSignal } = {},
+	options: {
+		ignoredOnly?: boolean;
+		includeIgnored?: boolean;
+		literalPathspecs?: boolean;
+		paths?: readonly string[];
+		signal?: AbortSignal;
+	} = {},
 ): Promise<void> {
-	const args = ["clean", options.ignoredOnly ? "-fdX" : options.includeIgnored ? "-fdx" : "-fd"];
+	const args = [options.literalPathspecs ? "--literal-pathspecs" : undefined, "clean"].filter(
+		(arg): arg is string => arg !== undefined,
+	);
+	args.push(options.ignoredOnly ? "-fdX" : options.includeIgnored ? "-fdx" : "-fd");
 	if (options.paths?.length) args.push("--", ...options.paths);
 	await runEffect(cwd, args, { signal: options.signal });
 }