Inconsistent answers between `bazel mod dump_repo_mapping` and `bazel mod show_repo` in bazel 7.7.1 when `WORKSPACE` depends on `MODULE.bazel`

### Description of the bug:

In some situations (see reproduction example below) bazel 7.7.1 (and also other bazel-7 versions) `bazel mod` gives inconsistent answers
- `bazel mod dump_repo_mapping ''` shows a repository as visible from the main repository, whereas
- `bazel mod show_repo` claims that this repository does not exist.

I have not found anything in the documentation that such a mismatch would be expected. It seems that this behavior occurs when a `WORKSPACE` file depends on a module pulled in by the `MODULE.bazel` file. While this seems contrived, the reproduction case is based on a [real-world example](https://github.com/build-server-protocol/build-server-protocol).

### Which category does this issue belong to?

External Dependency

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

Using bazelisk

```
~>cd $(mktemp -d)
/tmp/tmp.f8XQb62vAj>echo 7.7.1 > .bazelversion
/tmp/tmp.f8XQb62vAj>echo 'bazel_dep(name = "aspect_rules_lint", version = "1.0.0-rc10")' > MODULE.bazel
/tmp/tmp.f8XQb62vAj>cat > WORKSPACE <touch BUILD
/tmp/tmp.f8XQb62vAj>bazel mod dump_repo_mapping '' | jq .ktfmt
Starting local Bazel server and connecting to it...
(09:51:12) INFO: Invocation ID: bf188608-e00e-4f3c-8795-6d6ce960e354
(09:51:13) INFO: Current date is 2026-02-10
(09:51:13) no actions running
(09:51:14) no actions running
(09:51:15) no actions running
(09:51:16) no actions running
"ktfmt"
/tmp/tmp.f8XQb62vAj>bazel mod show_repo ktfmt
(09:51:37) INFO: Invocation ID: 3741266f-2bf0-4ca8-bb86-20cbe0b0ff2b
(09:51:37) INFO: Current date is 2026-02-10
(09:51:37) ERROR: In repo argument ktfmt: Module ktfmt does not exist in the dependency graph. (Note that unused modules cannot be used here). Type 'bazel help mod' for syntax and help.
/tmp/tmp.f8XQb62vAj>bazel mod show_repo @ktfmt
(09:51:54) INFO: Invocation ID: 3646e11b-e1e0-4fe2-80c3-6536c0728a30
(09:51:54) INFO: Current date is 2026-02-10
(09:51:54) ERROR: In repo argument @ktfmt: No repo visible as ktfmt from @main repository (Note that unused modules cannot be used here). Type 'bazel help mod' for syntax and help.
/tmp/tmp.f8XQb62vAj>bazel mod show_repo @@ktfmt
(09:52:04) INFO: Invocation ID: 9d3d98a6-008e-4e61-aaff-4aa7d262b21e
(09:52:04) INFO: Current date is 2026-02-10
(09:52:04) ERROR: In repo argument @@ktfmt: no such repo. Type 'bazel help mod' for syntax and help.
/tmp/tmp.f8XQb62vAj>
```

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

Ubuntu 24.04.3

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

release 7.7.1

### 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_

Reproduce the mismatch from the issue's minimal WORKSPACE and MODULE.bazel files on Ubuntu with Bazel 7.7.1. Compare `bazel mod dump_repo_mapping ''` with `bazel mod show_repo`, including the `ktfmt`, `@ktfmt`, and `@@ktfmt` forms. Done means repository visibility and lookup results are consistent for this WORKSPACE/MODULE.bazel dependency case.

Written by the indexing model from the issue text.