fix(tools): clarify import audit module inputs

[MarcZX10]

What

Clarifies that --modules reads original ELF modules. Converted .guest.prx files are PE outputs; their PS5 imports are already recorded in the per-module registry JSON passed as positional input. If a converted PE is passed to --modules, the error now explains the expected input and where to get the imports.

Addresses the usage ambiguity reported in #6378 without treating PE host exports as PS5 module exports.

Tested

Linux (Python 3):

• python3 -m unittest tools.tests.test_import_audit — 84 tests, 1 skipped.
• The PE input regression checks the converted .guest.prx filename and the actionable error.
• python3 tools/check_conventions.py --base upstream/main — passed.
• git diff --check — passed.

Checklist

• Based on current main; no other open PR implements the same behavior
• One topic per PR; follow-ups go in a new pull request
• No comments in code except technical debt
• Unimplemented paths throw
• No notes, investigation .md files or images added to the repository
• New third-party code is a submodule built from source
• Generic behavior, not specific to one title
• Depends on: none
• Unblocks: none
• GPUs tested: n/a
• AI-assisted: yes

[github-actions]

Some comparisons could not be completed because a pull request conflicts with the base branch. Review these shared files manually before concluding that there is no overlap.

Pull request	Shared files not compared
PR 3998	docs/user/USAGE.md
PR 4891	docs/user/USAGE.md
PR 5021	docs/user/USAGE.md
PR 5925	docs/user/USAGE.md
PR 6788	docs/user/USAGE.md
PR 7450	docs/user/USAGE.md
PR 7642	docs/user/USAGE.md