[Not Live; disabled by default] Add Claude Explain feature for AI-powered assembly explanations (#7749)

Add Claude Explain feature for AI-powered code explanations

This PR introduces Claude Explain, a new feature that provides AI-powered explanations of compiler output directly within Compiler Explorer.

Key features:

Claude Explain functionality:
  - New explain view pane
  - Explains compiler output with full context of source code and compilation output
  - Configurable audience level and explanation type
  - Response caching to improve performance and reduce API calls
  - Usage statistics display showing requests used and token counts

User experience:
  - Consent flow on first use explaining data handling and privacy
  - AI disclaimer banner warning about potential LLM inaccuracies
  - Respects "no-ai" directive in source code for users who don't want AI processing

Privacy and security:
  - Data sent to Anthropic's Claude API as documented in privacy policy
  - No data used for model training
  - Clear consent required before first use
  - Support for opting out via "no-ai" directive

The feature is marked as beta and can be enabled via configuration.

Co-authored-by: Claude <noreply@anthropic.com>

cypress.config.ts

@@ -1,8 +1,8 @@
 import {defineConfig} from 'cypress';
 
 export default defineConfig({
-    viewportWidth: 1000,
-    viewportHeight: 700,
+    viewportWidth: 1280,
+    viewportHeight: 1024,
     e2e: {
         baseUrl: 'http://127.0.0.1:10240/',
         supportFile: 'cypress/support/utils.ts',