src/zip_builtins.sh is not executable

### Description of the bug:

When trying to build bazel-8.4.2 from scratch (bootstrap) on Asahi Fedora linux (aarch64):

```
$ env EXTRA_BAZEL_ARGS="--tool_java_runtime_version=local_jdk" bash ./compile.sh
🍃 Building Bazel from scratch......
🍃 Building Bazel with Bazel.
.OpenJDK 64-Bit Server VM warning: Options -Xverify:none and -noverify were deprecated in JDK 13 and will likely be removed in a future release.
WARNING: /tmp/bazel_92HBeVxd/out/external/c-ares+/BUILD.bazel:42:10: in _copy_file rule @@c-ares+//:ares_build_h: target '@@c-ares+//:ares_build_h' depends on deprecated target '@@bazel_tools//src/conditions:host_windows_x64_constraint': No longer used by Bazel and will be removed in the future. Migrate to toolchains or define your own version of this setting.
WARNING: /tmp/bazel_92HBeVxd/out/external/c-ares+/BUILD.bazel:48:10: in _copy_file rule @@c-ares+//:ares_config_h: target '@@c-ares+//:ares_config_h' depends on deprecated target '@@bazel_tools//src/conditions:host_windows_x64_constraint': No longer used by Bazel and will be removed in the future. Migrate to toolchains or define your own version of this setting.
DEBUG: /tmp/bazel_92HBeVxd/out/external/protobuf+/protobuf.bzl:650:10: The py_proto_library macro is deprecated and will be removed in the 30.x release. switch to the rule defined by rules_python or the one in bazel/py_proto_library.bzl.
INFO: Analyzed target //src:bazel_nojdk (458 packages loaded, 12894 targets configured).
ERROR: /Data/Projects/bazel-8.4.2/src/BUILD:79:10: Symlinking //src:zip_builtins [for tool] failed: failed to create symbolic link 'bazel-out/aarch64-opt-exec-ST-fad1763555eb/bin/src/zip_builtins': file 'src/zip_builtins.sh' is not executable
Target //src:bazel_nojdk failed to build
INFO: Elapsed time: 6,635s, Critical Path: 0.77s
INFO: 523 processes: 493 internal, 30 local.
ERROR: Build did NOT complete successfully

ERROR: Could not build Bazel
```

I was able to get past this with "chmod a+x src/zip_builtins.sh".

### Which category does this issue belong to?

_No response_

### What's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

_No response_

### Which operating system are you running Bazel on?

_No response_

### What is the output of `bazel info release`?

_No response_

### If `bazel info release` returns `development version` or `(@non-git)`, tell us how you built Bazel.

_No response_

### What's the output of `git remote get-url origin; git rev-parse HEAD` ?

```text

```

### If this is a regression, please try to identify the Bazel commit where the bug was introduced with bazelisk --bisect.

_No response_

### Have you found anything relevant by searching the web?

_No response_

### Any other information, logs, or outputs that you want to share?

_No response_

Inspect src/zip_builtins.sh and the //src:zip_builtins target referenced in src/BUILD. Reproduce with the reported bootstrap command on aarch64, then verify that the source file is executable and the target builds successfully without the symlink error.

Written by the indexing model from the issue text.