fix: render LaTeX math in chat messages

[nimitbhardwaj]

Summary

Fixes #1167 - LaTeX math not rendering in chat

Changes

• webchat.rs: CSP updated to allow https://cdn.jsdelivr.net for scripts, styles, fonts, and connect-src
• chat.js: MutationObserver in init() watches for new .message-bubble elements and calls renderLatex() automatically

Testing

• cargo clippy --workspace --all-targets -- -D warnings passes
• cargo test --workspace passes
• Live integration tested (if applicable)

Security

• No new unsafe code
• No secrets or API keys in diff
• User input validated at boundaries

[nimitbhardwaj]

@jaberjaber23 you can re-run the action, that format issue of the PR will be fixed in CI/CD, I initially used the wrong format for the PR.

May be its worth mentioning in AGENTS.md or CLAUDE.md about the format of the PR to be generated.