Add RECOMMENDED label normalization to spec #133
Description
Add a RECOMMENDED (not MUST) label normalization rule to ISSUE-FORMAT.md Section 4.7:
'Implementations SHOULD normalize labels to lowercase before comparison during merge operations. Implementations that preserve original case for display SHOULD still use case-insensitive comparison for merge logic.'
This addresses the case-variant merge problem (bug vs Bug creating duplicates) without forcing loss of intentional casing (iOS, API, UI).
Also add to Section 6.3.1:
- Document that case-insensitive comparison is RECOMMENDED for merge
- Note that git issue lint SHOULD detect case-variant duplicates
No implementation change required for v1.1 -- this is a spec clarification. Implementation can follow in v1.2 with an optional --normalize flag on git issue edit.