#7246 fix(secrets): preserve caret when revealing values

Summary

• Preserve editable secret values in the input while applying visual masking
• Keep fixed-length placeholders for read-only and withheld secrets
• Add caret, reveal, editability, and re-mask regression coverage

Type of Change

• Bug fix

Testing

Targeted secret-value-field Vitest suite, full lint, block registry checks, 39 repository audits, and docs manifest validation.

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)