[Feature Request] Add 'feedback' label for CLI feedback command

[OmniaZ1]

Problem
The openspec feedback command fails with HTTP 404: label 'feedback' not found because the OpenSpec repository lacks this label.

Current Labels
The repo has 29 labels (bug, documentation, enhancement, etc.) but no feedback label.

Solution
Create a feedback label with:

• Description: User feedback, suggestions, or praise for OpenSpec CLI
• Color: #FBA4D4 (pink - distinguishing from bug/enhancement)

Impact

• Enables openspec feedback command to work without fallback
• Clear categorization for user feedback issues
• Low effort, high value

Alternative
If creating the label isn't preferred, the CLI could fallback to using question or enhancement labels when feedback doesn't exist.