fix: parse commands with CRLF line endings

[thc1006]

Description

getCommandArgs and getLineArgs split the comment body on \n but never strip the \r, so with a CRLF comment every line except the last keeps a trailing carriage return. /kind enhancement\r is then filtered out because enhancement\r is not an allowed label, /milestone ...\r misses the milestone by name, and only the final line, which has no \r, works.

That is exactly #81: /kind, /milestone, and /area only took effect on whichever command was on the last line, and reordering changed which one worked. GitHub delivers comment bodies with CRLF, so this hits any comment with more than one command.

This normalizes \r\n and a lone \r to \n before splitting, through a small splitLines helper used by both functions.

Fixes #81

Testing

• npm run all passes (build, lint, pack, test)
• a CRLF comment with /kind and /area returns each command's args without a trailing carriage return
• getLineArgs returns a milestone title with no trailing carriage return
• confirmed both tests fail without the change

Checklist:

• I ran npm run all to lint and build my code
• No new dependencies
• I have performed a self review of my own code
• I have commented my code, particularly in hard to understand areas
• I have made corresponding changes to the documentation (no documentation changes needed)
• My changes generate no new warnings