FeedbackKit 2.3.7

Let native iOS sheet and navigation containers provide page backgrounds, avoiding solid content rectangles and seams around the grabber and safe areas while dragging.

• Covers questionnaires, the feedback center, activity, personal feedback, roadmap, releases, diagnostics, and identity pages.
• Preserves button, card, input, form-row, and footer backgrounds.
• Keeps the existing macOS window surface and public APIs.

Validation: all 236 Swift package tests and the generic iOS package build passed. Independent review found no issues.

PR: #63