fix: ChatGPT fetch interception failure + bump to 2.0.6

ChatGPT (and potentially other AI services) calls fetch() with a
Request object as the first argument: fetch(new Request(url, opts))
instead of fetch(url, opts). The interceptor only handled the second
form, so ChatGPT's conversation requests passed through unmodified.

Fixed by handling both fetch signatures:
- fetch(url, options) — existing path
- fetch(Request) — new: extracts URL, method, headers, reads body
  via request.text() for JSON/text content types

Also handles non-string body types:
- Blob → text via blob.text()
- ArrayBuffer → text via TextDecoder
- URLSearchParams → string via toString()

These cover the various ways modern frameworks call fetch().

https://claude.ai/code/session_01SWSwDfMVij53bCTNSCLMwn

src/options/options.html

@@ -591,7 +591,7 @@
     </section>
 
     <footer>
-      <p>Silent Send v2.0.5</p>
+      <p>Silent Send v2.0.6</p>
     </footer>
   </div>