fix(build): preserve LF for shell entrypoints

[xumian520]

What does this PR do?

Preserve LF checkout semantics for shell entrypoints so Windows clones with core.autocrlf=true can run repository scripts directly from WSL or MSYS. Without this rule, the shebang can be checked out as CRLF and fail with env: $'bash\r': No such file or directory.

This adds a shell line-ending contract test and runs it before the compiler-heavy suite. The test checks all tracked *.sh files and shell hook entrypoints with git check-attr.

Validation

• bash tests/test_shell_line_endings.sh: 60/60 entrypoints passed
• bash scripts/build.sh: passed
• Version smoke test: codebase-memory-mcp dev
• git diff --check: passed
• Full suite: 6,614 passed / 6 failed / 4 skipped. The six failures are unrelated WSL/DrvFs/test-infrastructure failures, so this does not claim a fully green local suite.

Checklist

• Every commit is signed off (git commit -s) — required, CI rejects unsigned commits (DCO, see CONTRIBUTING.md)
• Tests pass locally (make -f Makefile.cbm test)
• Lint passes (make -f Makefile.cbm lint-ci)
• New behavior is covered by a test (reproduce-first for bug fixes)

[DeusData]

Thank you for the contribution and for adding a regression contract around LF shell entrypoints on Windows checkouts. This is now triaged as a high-priority Windows build bug for 0.9.1-rc. Our community PR queue is currently quite full, so it may take a little time before we can complete the review and, if approved, merge it. We are doing our best to support community contributions and will return with code-grounded feedback as capacity opens.