fix: escape less-than character in search-architecture.mdx to resolve MDX parsing error

Changed '<10ms' to 'Sub-10ms' to avoid MDX interpreting the < character as an HTML tag opening, which was causing deployment failure.

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Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

docs/public/architecture/search-architecture.mdx

@@ -405,7 +405,7 @@ function escapeFTS5Query(query: string): string {
 
 ## Performance
 
-**FTS5 Full-Text Search:** <10ms for typical queries
+**FTS5 Full-Text Search:** Sub-10ms for typical queries
 
 **MCP Overhead:** Minimal - simple protocol translation