Fix ABNF grammar: replace CRLF with LF token

[remenoscodes]

Section 4.8 of ISSUE-FORMAT.md defines CRLF = %x0A, which contradicts RFC 5234 where CRLF means %x0D.0A. This misleads readers cross-referencing the RFC.

Fix:

• Replace all 'CRLF' tokens with 'LF = %x0A' in the grammar
• Add 'title = 1*TEXT-NO-LF' (require at least one character, reject empty titles)
• Clarify the 72-char title recommendation as SHOULD, specify behavior when exceeded (accept with no truncation)

These are non-breaking spec clarifications. No implementation changes needed beyond validation.