fix: reveal/highlight scoped to chat area only + remove footer link — v2.0.14

Reveal mode and highlights were replacing text in sidebars, navigation,
headers, repo names, and other non-chat UI elements. Now skips:
- <nav>, <aside>, <header>, <footer> elements
- Elements with role="navigation", role="banner", role="complementary"
- Elements with class names containing sidebar, nav, menu, header

Added isInNonChatArea() check to all five code paths:
- revealInElement, unrevealInElement, highlightMatches
- MutationObserver addedNodes and characterData handlers

Also:
- Removed footer Options link (redundant with 5th Options tab)
- Updated README: ChatGPT marked as Tested

https://claude.ai/code/session_01SWSwDfMVij53bCTNSCLMwn

src/popup/popup.html

@@ -262,7 +262,6 @@
         PPI in images, file uploads, unusual name forms, or data you forgot to
         configure. Always verify sensitive messages before sending.
       </div>
-      <a href="#" id="btnOptions">Options</a>
     </footer>
   </div>