make claude output formatted code

[nullhook]

Resolves brave/brave-browser#35380

Submitter Checklist:

• I confirm that no security/privacy review is needed and no other type of reviews are needed, or that I have requested them
• There is a ticket for my issue
• Used Github auto-closing keywords in the PR description above
• Wrote a good PR/commit description
• Squashed any review feedback or "fixup" commits before merge, so that history is a record of what happened in the repo, not your PR
• Added appropriate labels (QA/Yes or QA/No; release-notes/include or release-notes/exclude; OS/...) to the associated issue
• Checked the PR locally:
  • npm run test -- brave_browser_tests, npm run test -- brave_unit_tests wiki
  • npm run lint, npm run presubmit wiki, npm run gn_check, npm run tslint
• Ran git rebase master (if needed)

Reviewer Checklist:

• A security review is not needed, or a link to one is included in the PR description
• New files have MPL-2.0 license header
• Adequate test coverage exists to prevent regressions
• Major classes, functions and non-trivial code blocks are well-commented
• Changes in component dependencies are properly reflected in gn
• Code follows the style guide
• Test plan is specified in PR before merging

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on
• All relevant documentation has been updated, for instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protections
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Web-Compatibility-Exceptions-in-Brave
  • https://github.com/brave/brave-browser/wiki/QA-Guide
  • https://github.com/brave/brave-browser/wiki/P3A

Test Plan:

[petemill]

works well

[brave-builds]

A Storybook has been deployed to preview UI for the latest push

[stephendonner]

Verification PASSED using

Brave | 1.64.5 Chromium: 121.0.6167.75 (Official Build) nightly (64-bit)
-- | --
Revision | 2bf3fedfbbe00d5306677ee5f480580a4c401018
OS | Windows 10 Version 22H2 (Build 19045.3930)

Steps:

1. installed 1.64.5
2. launched Brave
3. loaded wired.com
4. clicked on Leo in the sidebar
5. clicked on Summarize this page
6. clicked on Accept and begin
7. typed Write me a "Hello, world!" program in C++
8. waited for and copied code output
9. did the same for JavaScript
10. did the same for Python

Confirmed the code output was correctly formatted inline, as were the "copy code" button's output

C++

before (1.64.3)	after (1.64.5)

Copied code sample:

#include <iostream>
using namespace std;

int main() {
  cout << "Hello, World!" << endl; 
  return 0;
}

JavaScript

Python