PR Checklist

• The commit message follows the guidelines
• Tests for the changes have been added / updated
• Docs have been added / updated (not applicable)

PR Type

• Bugfix
• Feature
• Code style update
• Refactoring
• Build related changes
• CI related changes

What is the current behavior?

When Nest cannot resolve a dependency, the error message produced by
UNKNOWN_DEPENDENCIES_MESSAGE has two minor rough edges:

1. For import-type issues (where the dependency name is genuinely unknown),
   the word "dependency" is used as a generic stand-in, resulting in phrasing like:

   Please make sure that the argument dependency at index [0] …

2. The message ends with "context", while users typically reason
   about their applications in terms of modules, e.g.:

   … is available in the RootTestModule context.

Discussion reference: #16491

What is the new behavior?

• The token name is displayed only when it is actually defined.
  If the name is unknown, the message now reads:

  argument at index [N]

  (without a misleading placeholder word)

• "context" is replaced with "module" so the phrasing aligns with
  how users reason about application structure.

Before

Nest can't resolve dependencies of the CatService (?, CatService).
Please make sure that the argument dependency at index [0] is available in the current context.

After

Nest can't resolve dependencies of the CatService (?, CatService).
Please make sure that the argument at index [0] is available in the current module.

String and symbol tokens continue to render correctly
(e.g. "FooRepository", Symbol(MY_TOKEN)).

Does this PR introduce a breaking change?

• No

This is strictly a developer-experience wording refinement.
No public APIs, runtime behavior, or error types are changed.

All unit and integration tests pass.