refactor: optimize selection capture and remove dead code

- Removed Node.js export from capture.js (browser-only code)
- Simplified selection capture to avoid expensive getComputedStyle() calls
- Added performance notes for selection clipping
- Aligned content.js with capture.js implementation

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

browser-extension/scripts/capture.js

@@ -46,6 +46,8 @@ function captureFullPage() {
 
 /**
  * Capture selected content from the page
+ * Note: For performance, selection clipping uses basic HTML structure without
+ * per-element computed styles. The resulting PDF will use browser default styles.
  * @returns {Object} Selection data with HTML, text, and metadata
  */
 function captureSelection() {
@@ -92,11 +94,3 @@ function captureSelection() {
         timestamp: new Date().toISOString()
     };
 }
-
-// Export functions for use in other scripts
-if (typeof module !== 'undefined' && module.exports) {
-    module.exports = {
-        captureFullPage,
-        captureSelection
-    };
-}