Narrow claude.ai/code interception to user-input fields

Replaces the blanket skip on claude.ai/code with a targeted walker so
the user's prompt and pasted attachments still get substituted, but
tool_use / tool_result / system / IDs / metadata pass through verbatim.

Fields touched:
- top-level prompt and input (classic claude.ai shape)
- attachments[].extracted_content and attachments[].file_name
- messages[].content (or text parts) when role === 'user'

FormData uploads continue to flow through DocumentScanner since they
are user input. Raw non-JSON bodies are skipped on this path because
they are typically tool traffic, not user text.

https://claude.ai/code/session_01Y2YprLMx348eWD5C9Z4zpV

src/content/injector.js

@@ -15,15 +15,6 @@
   if (window.__silentSendInjected) return;
   window.__silentSendInjected = true;
 
-  // Skip Claude Code (web). Its tool-call traffic carries real paths/commands
-  // that must reach the runtime verbatim — substitution breaks execution.
-  if (
-    location.hostname === 'claude.ai' &&
-    /^\/code(\/|$)/.test(location.pathname)
-  ) {
-    return;
-  }
-
   // Merge active profiles into flat identity object
   function mergeProfiles(data) {
     const profiles = data?.profiles || [];