fix(libc): resolve case differences in guest paths and mounts

[TibixDev]

What

Resolve ASCII case differences in guest paths and mount aliases. Prefer exact names, preserve new filenames, and reject ambiguous fallback matches. Do not cache directory results, so renames stay visible.

Supersedes #1079. This version also handles mount aliases, blocked mounts, dangling symlinks, and ambiguous names. Tests use guest file APIs as well as path resolution. #1101 concerns Windows module dependency names, a separate path.

Tested

Fedora 44, Release: path-case, app-content, working-directory, directory, and filesystem tests. Covers open, read, create, stat, rename, removal, aliases, and conflicting names. Contribution checks pass.

The combined fork loaded Skyrim files that differ in case from requested names. This isolated branch was not run in-game. Unicode folding and console behavior for case collisions remain unverified; Windows was not tested.

Checklist

• Current main; prerequisite and competing implementation checked.
• One topic.
• No new code comments.
• Unsupported paths still throw; UI stubs are documented.
• No notes, logs, or images in the repository.
• No new third-party code.
• General behavior.
• Depends on: none (fix(appcontent): track temporary storage mounts #1320 is merged).
• AI-assisted: yes.

[TibixDev]

Rebased on bc1fbe81. Rebased the path-case change onto the updated #1320 parent. Kept exact-name preference and ambiguous-name rejection.

Fedora 44 Release: guest_path_case_tests, guest_appcontent_tests, guest_working_directory_tests, guest_directory_tests, guest_filesystem_tests build; the targeted tests and contribution checks pass. Windows CI is pending.

[adriadam10]

Rebased onto current main (#1320 is merged, so its commit is dropped) and added one commit: the new test used a title's file names (Skyrim.*); it now uses generic ones. Also updated the PR body (no longer depends on #1320).

Checked: full build and ctest on the rebase (452/452); guest_path_case fails without the change; exact-name preference, ambiguous-name rejection and alias handling behave as described. Not run: a real title, Windows at runtime, Unicode folding.

#1079 touches the same function and test file; this one supersedes it, so #1079 should be closed once this lands. Merging when CI is green.

[github-actions]

Other open pull requests touch the same code. Merging one will break the other, or both implement the same thing. If this one builds on them, list them in Depends on.

Pull request	Conflicting files (lines on main)	Same exports	Same new files
#1535	docs/dev/TechnicalDebt.md L329