chore: scaffold Vite + Vitest + PixiJS project

src/main.js

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+console.log('Probability — boot ok');

src/styles.css

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+* { margin: 0; padding: 0; box-sizing: border-box; }
+html, body { height: 100%; background: #05070d; color: #bfe8ff; font: 13px/1.5 "Segoe UI", system-ui, sans-serif; }
+body { display: flex; }
+#stage { flex: 1; height: 100%; position: relative; }
+#panel { width: 320px; height: 100%; overflow-y: auto; padding: 12px; background: #0a0e18; border-left: 1px solid #1b2940; }
+#panel h2 { font-size: 13px; color: #69e6ff; text-transform: uppercase; letter-spacing: 1px; margin: 14px 0 6px; }
+#panel button { background: #11203a; color: #9fd8ff; border: 1px solid #28456e; border-radius: 3px; padding: 3px 9px; margin: 2px; cursor: pointer; font-size: 12px; }
+#panel button:hover { background: #1b3358; }
+#panel button.active { background: #0e4a5e; border-color: #2ec5e0; color: #d6f6ff; }
+#panel table { width: 100%; border-collapse: collapse; margin: 4px 0; }
+#panel td, #panel th { padding: 2px 4px; text-align: left; border-bottom: 1px solid #15233a; font-size: 12px; }
+#log { font-size: 11px; color: #6f93b8; max-height: 160px; overflow-y: auto; }
+.banner { position: absolute; inset: 0; display: flex; align-items: center; justify-content: center;
+  font-size: 42px; color: #69e6ff; background: rgba(5,7,13,.75); z-index: 10; text-shadow: 0 0 24px #2ec5e0; }
+.muted { color: #5d7b9a; }