fix: replace "Fast prototyping" with "Rapid prototyping" in input handling

https://claude.ai/code/session_01M6YRViV1SVqE9DoZwXMbbd

Author: claude

docs/technical/dx.md

@@ -54,7 +54,7 @@ START-OF-SELECTION.
   MESSAGE |Input: { pa_arbgb }| TYPE `I`.
 ```
 Benefits:
-- Fast prototyping with minimal code
+- Rapid prototyping with minimal code
 - Built-in input handling and event processing
 - Full-stack behavior with no setup