<!-- This is an auto-generated description by cubic. -->
## Summary by cubic
Adds web search to Dyad Pro chats with a new UI, tag parsing, and a Pro
Mode toggle that wires through to the engine.
- **New Features**
- Pro Mode toggle: “Web Search” (settings.enableProWebSearch).
- New custom tags: dyad-web-search, dyad-web-search-result, dyad-read.
- Collapsible Web Search Result UI with in-progress badge and markdown
rendering.
- Engine integration: passes enable_web_search and activates DyadEngine
when web search is on.
<!-- End of auto-generated description by cubic. -->
