MCP registry builder skips Text blocks in component docs #584

The MCP registry builder (mcp/lib/ruby_ui/mcp/builders/registry_builder.rb, parse_docs_source) only picks up single-line Heading(level: N) { "..." }, P { "..." } and VisualCodeExample blocks. Multi-line Text do ... end paragraphs built from plain, InlineLink and InlineCode are skipped, so their prose never reaches docs_markdown.

Three components use these blocks today: chart, form and masked_input. The Chart entry, for example, has an empty ## Introduction section, and the note about the --chart-1 to --chart-5 defaults added in #582 is missing too.

Proposed fix: have the parser serialize Text blocks to Markdown (plain as text, InlineLink as [text](href), InlineCode as backticks), then rebuild mcp/data/registry.json.

Found by cubic while reviewing #582.

🤖 Generated with Claude Code