Phase E/I: expose evalScript() as a permanent debug API, finalize README

Promotes vpinball_wasm_eval_script from a one-off validation hack to a
supported PinballInstance.evalScript() method (runs arbitrary VBScript
against the live table via the interpreter's own debug-console entry
point) - useful standalone, and it's what confirms the DMD script API
rides the same execution path already proven by real flipper input.

Rewrites the README's Status/Roadmap/Known limitations to reflect
tonight's actual, hands-on-confirmed state: keyboard input, audio, and
VBScript-driven gameplay all verified end-to-end (not just code
review); two more real engine bugs found and fixed (GL back buffer
sized in logical instead of device pixels; back buffer never resynced
on resize, breaking fullscreen); the default table swap and why;
B2S backglass explicitly assessed and declined for now, with the
concrete reasons (no plugin subsystem wired for this build, no test
table to validate against) rather than left as a vague TODO.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

examples/basic/index.html

@@ -77,6 +77,7 @@
 				progressBar.style.width = `${Math.round(fraction * 100)}%`;
 			},
 		});
+		window.pinball = pinball; // for console access (e.g. pinball.evalScript(...))
 
 		startButton.disabled = false;
 		startButton.textContent = 'Start';