Add fullscreen firework emoji confetti and fix Linux URL paste.

Sparkle 🎆/🎇 from the jumbo emoji with a lightweight particle fountain that piles on the floor. Prefer text/plain over sticky clipboard images on Linux so address-bar URLs do not also attach a leftover bitmap.

src/app/features/room/emoji-confetti/EmojiConfettiBurstCanvas.tsx

@@ -1,4 +1,4 @@
-import React, { useEffect, useMemo, useRef, useState } from 'react';
+import React, { useEffect, useMemo, useRef } from 'react';
 import { createPortal } from 'react-dom';
 import { EmojiConfettiBurst } from './types';
 import { findJumboEmojiElement, getLocalBurstCanvasSize } from './findJumboMount';
@@ -8,6 +8,14 @@ import {
   spawnEmojiBurst,
   stepBurstParticles,
 } from './emojiBurstEngine';
+import { getEmojiBurstProfile, isFullscreenBurstEmoji } from './emojiParticleProfiles';
+import {
+  createFireworkSim,
+  drawFireworkSim,
+  FireworkSim,
+  getFireworkDpr,
+  stepFireworkSim,
+} from './fireworkParticleEngine';
 
 const MAX_DPR = 2;
 
@@ -17,6 +25,147 @@ type EmojiConfettiBurstCanvasProps = {
 };
 
 export function EmojiConfettiBurstCanvas({ burst, onComplete }: EmojiConfettiBurstCanvasProps) {
+  const primaryEmoji = burst.emojis[0] ?? '🎉';
+  const fullscreen = isFullscreenBurstEmoji(primaryEmoji);
+
+  if (fullscreen) {
+    return <FireworkBurstCanvas burst={burst} primaryEmoji={primaryEmoji} onComplete={onComplete} />;
+  }
+
+  return <LocalBurstCanvas burst={burst} primaryEmoji={primaryEmoji} onComplete={onComplete} />;
+}
+
+type BurstCanvasProps = {
+  burst: EmojiConfettiBurst;
+  primaryEmoji: string;
+  onComplete: (burstId: string) => void;
+};
+
+function FireworkBurstCanvas({ burst, primaryEmoji, onComplete }: BurstCanvasProps) {
+  const canvasRef = useRef<HTMLCanvasElement>(null);
+  const simRef = useRef<FireworkSim | null>(null);
+  const frameRef = useRef<number | null>(null);
+  const lastFrameTimeRef = useRef<number | null>(null);
+  const spawnedRef = useRef(false);
+  const onCompleteRef = useRef(onComplete);
+  onCompleteRef.current = onComplete;
+
+  useEffect(() => {
+    if (!canvasRef.current || spawnedRef.current) return undefined;
+
+    const reducedMotion = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
+    if (reducedMotion) {
+      onCompleteRef.current(burst.id);
+      return undefined;
+    }
+
+    const canvas = canvasRef.current;
+    const context = canvas.getContext('2d', { alpha: true });
+    if (!context) {
+      onCompleteRef.current(burst.id);
+      return undefined;
+    }
+    context.imageSmoothingEnabled = false;
+
+    spawnedRef.current = true;
+
+    const resize = () => {
+      const dpr = getFireworkDpr();
+      const width = window.innerWidth;
+      const height = window.innerHeight;
+      canvas.width = Math.round(width * dpr);
+      canvas.height = Math.round(height * dpr);
+      canvas.style.width = `${width}px`;
+      canvas.style.height = `${height}px`;
+      return { width, height, dpr };
+    };
+
+    const { width, height } = resize();
+    const jumbo = findJumboEmojiElement(burst.targetEventId);
+    const jumboRect = jumbo?.getBoundingClientRect();
+    const origin = {
+      x: jumboRect ? jumboRect.left + jumboRect.width / 2 : burst.origin.x,
+      y: jumboRect ? jumboRect.top + jumboRect.height / 2 : burst.origin.y,
+      maskRadius: burst.origin.maskRadius ?? 36,
+    };
+
+    // Clamp origin into the viewport so off-screen messages still blast on-screen.
+    origin.x = Math.min(width - 24, Math.max(24, origin.x));
+    origin.y = Math.min(height - 24, Math.max(24, origin.y));
+
+    const profile = getEmojiBurstProfile(primaryEmoji);
+    simRef.current = createFireworkSim(width, height, origin, primaryEmoji, profile);
+
+    const onResize = () => {
+      // Extra Things: match CSS size; sim keeps its launch-time dimensions.
+      resize();
+    };
+    window.addEventListener('resize', onResize);
+
+    const tick = (now: number) => {
+      const sim = simRef.current;
+      if (!sim) return;
+
+      const last = lastFrameTimeRef.current ?? now;
+      const dtSeconds = Math.min((now - last) / 1000, 0.05);
+      lastFrameTimeRef.current = now;
+
+      const alive = stepFireworkSim(sim, now, dtSeconds);
+      context.setTransform(1, 0, 0, 1, 0, 0);
+      context.clearRect(0, 0, canvas.width, canvas.height);
+
+      if (alive) {
+        drawFireworkSim(context, sim, now);
+        frameRef.current = requestAnimationFrame(tick);
+        return;
+      }
+
+      onCompleteRef.current(burst.id);
+      frameRef.current = null;
+      lastFrameTimeRef.current = null;
+    };
+
+    lastFrameTimeRef.current = performance.now();
+    frameRef.current = requestAnimationFrame(tick);
+
+    return () => {
+      window.removeEventListener('resize', onResize);
+      if (frameRef.current !== null) {
+        cancelAnimationFrame(frameRef.current);
+        frameRef.current = null;
+      }
+      simRef.current = null;
+    };
+  }, [burst.id, burst.origin.maskRadius, burst.origin.x, burst.origin.y, burst.targetEventId, primaryEmoji]);
+
+  return createPortal(
+    <div
+      aria-hidden
+      style={{
+        position: 'fixed',
+        inset: 0,
+        width: '100vw',
+        height: '100vh',
+        pointerEvents: 'none',
+        zIndex: 40,
+      }}
+    >
+      <canvas
+        ref={canvasRef}
+        style={{
+          position: 'absolute',
+          inset: 0,
+          width: '100%',
+          height: '100%',
+          pointerEvents: 'none',
+        }}
+      />
+    </div>,
+    document.body
+  );
+}
+
+function LocalBurstCanvas({ burst, primaryEmoji, onComplete }: BurstCanvasProps) {
   const canvasRef = useRef<HTMLCanvasElement>(null);
   const layerRef = useRef<HTMLDivElement>(null);
   const particlesRef = useRef<BurstParticle[]>([]);
@@ -89,13 +238,7 @@ export function EmojiConfettiBurstCanvas({ burst, onComplete }: EmojiConfettiBur
       canvas.style.width = `${canvasSize}px`;
       canvas.style.height = `${canvasSize}px`;
 
-      spawnEmojiBurst(
-        particlesRef.current,
-        burst.id,
-        localOrigin,
-        burst.emojis[0] ?? '🎉',
-        performance.now()
-      );
+      spawnEmojiBurst(particlesRef.current, burst.id, localOrigin, primaryEmoji, performance.now());
 
       const tick = (now: number) => {
         updateLayerPosition();
@@ -152,7 +295,7 @@ export function EmojiConfettiBurstCanvas({ burst, onComplete }: EmojiConfettiBur
       window.clearInterval(retry);
       frameCleanup?.();
     };
-  }, [burst.emojis, burst.id, burst.targetEventId, canvasSize, localOrigin]);
+  }, [burst.id, burst.targetEventId, canvasSize, localOrigin, primaryEmoji]);
 
   return createPortal(
     <div