nx_browser_demo_hello.nx

nx_browser_demo_hello.nx -- visible demo program. Paints "HELLO WORLD" into a 96x16 framebuffer using the expanded 5x7 font (now supports H E L O W R D plus the digits/period/space from the prior subset). Dumps to stdout as ASCII art. Composes the same Phase 4 + 5 stack as nx_browser_demo_42 but renders English text instead of digits, proving the font expansion works end-to-end.