test: add comprehensive suites for git states, tar archives, exit codes, loc syntax, and reparse points

[fxrdhan]

Summary

Coverage and rigor by eliminating all remaining testing blindspots:

• Git Complex States & Conflicts: Integration tests for merge conflicts (UU, AA, UD, DU), detached HEAD repositories, and rebase-in-progress state resilience.
• Deep Tar Archive Inspection: Tests internal symlinks, GNU LongName headers (> 100 characters), and JSON output under --inspect-archives.
• Process Exit Codes & Permissions: Verification of exit code contracts for SUCCESS (0), OPTIONS_ERROR (3), PERMISSION_DENIED (13), and missing path errors.
• LOC Engine Syntax Edge-Cases: Tests nested multiline block comments in Rust, Python triple quotes, C++ raw strings, Shell quotes, and Ada/Lua comment isolation alongside the code + comments + blanks == lines invariant.
• Windows Reparse Points & Junctions: Portable tests for NTFS Directory Junctions (IO_REPARSE_TAG_MOUNT_POINT), AppExecLinks, and NT native prefix normalization.

Type of Change

• ⚡ Performance improvement / Test Suite Hardening

Related Issues

• Resolves: N/A

How Has This Been Tested?

• Testing commands executed:
  • cargo nextest run --workspace (2,312 integration & unit tests passed)
  • cargo test --doc (29 doc-tests passed)
  • cargo clippy --all-targets -- -D warnings (0 warnings)
  • cargo fmt --check (passed)
• Platforms verified:
  • macOS arm64 (local)
  • Linux x86_64 / Windows (via CI)

Contributor Checklist

• My commits follow Conventional Commits format
• Tests covering the changes have been added/updated
• cargo clippy --all-targets passes with no warnings
• cargo nextest run (or cargo test) passes
• cargo fmt --check / nix fmt passes
• License headers (SPDX / REUSE) are properly preserved/added