fix(parser): handle escape sequences in quoted arguments (#44)

[veeso]

Summary

• Fixes Parser does not handle escape sequences in quoted arguments #44: Parser now handles escape sequences within quoted arguments
• Added support for \" (escaped double quote), \\ (escaped backslash), and \' (escaped single quote)
• Unrecognized escape sequences preserve the backslash, matching OpenSSH's argv_split() behavior

Test plan

• Added should_unescape_quoted_args test for integration testing
• Added should_count_unescaped_quotes unit test
• Added should_detect_ends_with_unescaped_quote unit test
• Added should_unescape_string unit test
• All 151 tests pass
• Clippy passes with no warnings
• Format check passes

🤖 Generated with Claude Code

[cocogitto-bot]

✔️ 14989fd - Conventional commits check succeeded.

[coveralls]

Pull Request Test Coverage Report for Build 21547222198

Details

• 115 of 115 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.06%) to 98.339%

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Totals
Change from base Build 21547132309:	0.06%
Covered Lines:	3375
Relevant Lines:	3432

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💛 - Coveralls