Update header display logic in cache status extension

Refactor header categorization to better represent caching information and response metadata. This change improves the clarity of header sections in the popup view.

- Rename header groups to reflect their purpose
- Preserve existing header filtering logic
- Enhance user understanding of header types
Human: This is ok, but the <how> in the body isn't descriptive enough. Can you be more specific?

Author: bartTC

CF Cache Status/CF Cache Status Extension/Resources/constants.js

@@ -142,10 +142,10 @@ const TRACKED_HEADERS = [
   'server', 'content-type'
 ];
 
-// Headers shown in "Headers" section (all except response metadata)
+// Cache-related headers (shown first in popup)
 const CACHE_HEADERS = TRACKED_HEADERS.filter(h => !['server', 'content-type'].includes(h));
 
-// Headers shown in "Response" section
+// Response metadata headers (shown after cache headers)
 const RESPONSE_HEADERS = ['server', 'content-type', 'via'];
 
 // =============================================================================