chore: LF line endings everywhere

[rent-a-developer]

Closes #26.

Every text file is now LF, in the repository and in the working tree, on every OS. The repository has no
batch files, so there is no exception.

Commits

1. test: expect LF in SQL fragment assertions — seven assertions compared an SQL fragment taken
   verbatim from a multi-line raw string literal against Environment.NewLine. C# does not normalize
   newlines inside literals, so a literal's value is the file's bytes. That only matched while .cs
   checked out platform-native. With LF everywhere the expected value is a plain LF escape. Without this
   the tests fail on Windows while CI, which runs them on Linux, stays green.
2. chore: rename tidy-cs.ps1 to tidy-code.ps1 — the script covers more than C#. All references updated.
3. chore: store every text file as LF — .gitattributes reduced to * text=auto eol=lf plus the
   binary list; .editorconfig sets end_of_line = lf; CI gains a renormalization guard;
   CONTRIBUTING.md documents the policy.
4. test: normalize the expected ToString output to the host newline — InterpolatedSqlStatement.ToString builds its output with AppendLine and ReplaceLineEndings, so it is host-native. The expected raw string literal is now always LF, which no longer matches on Windows.

git add --renormalize . was a no-op — the index was already all-LF — so there is no renormalization
commit and no new .git-blame-ignore-revs entry.

Why

The per-type table needed a decision for every new file type, and the types nobody listed silently got
whatever each contributor's core.autocrlf produced. .cs checked out CRLF on Windows and LF on Linux,
so byte-level tooling saw different bytes per OS. The explicit eol= now overrides core.autocrlf and
core.eol, so contributors need no git configuration at all.

scripts/tidy-code.ps1 needed no change for this: it runs CSharpier last, and CSharpier honours
end_of_line = lf, so any file left as CRLF by another tool is rewritten to LF automatically.

For contributors

• Nothing to configure. core.autocrlf no longer matters.
• Optional one-time clone refresh for an all-LF working tree — commit or stash first, as the second
  command discards uncommitted work:

  git rm -r --cached . -q
  git reset --hard

• If a tool writes CRLF into your working tree, git status shows the file as modified while
  git diff stays empty. Run pwsh -File scripts/tidy-code.ps1, or git checkout -- <path>.
• With core.safecrlf=true (not a default) git add refuses such a file; run the tidy script, or set
  core.safecrlf warn.
• Open branches rebase cleanly; a line-ending conflict resolves with git merge -X renormalize.

Verification

• dotnet test passes on Windows and on Linux.
• lint green, including the new renormalization guard.
• git ls-files --eol shows no i/crlf or i/mixed entries.
• No reference to tidy-cs.ps1 remains.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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