Fix what JSR's type check (Deno's TypeScript) rejects

Deno's TypeScript makes typed arrays generic over their buffer: three variables in
the AV1 and AVIF code took a narrower type from their initializer, so
deno publish failed to type check.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Lfv41PqHEGbU7SLg5onpG1

Author: matmen

src/codecs/av1/ipred.ts

@@ -327,10 +327,10 @@ function filterIntra(dst: Uint16Array, d: number, stride: number, width: number,
     const e = edgeBuffer;
     const taps = filter * 56;
     // the top row comes from the edge buffer for the first two rows, from the block afterwards
-    let topArr = e, top = EDGE + 1;
+    let topArr: Uint16Array = e, top = EDGE + 1;
     for (let y = 0; y < height; y += 2) {
-        let tlArr = e, tl = EDGE - y;
-        let leftArr = e, left = tl - 1, leftStride = -1;
+        let tlArr: Uint16Array = e, tl = EDGE - y;
+        let leftArr: Uint16Array = e, left = tl - 1, leftStride = -1;
         for (let x = 0; x < width; x += 4) {
             const p0 = tlArr[tl];
             const p1 = topArr[top], p2 = topArr[top + 1], p3 = topArr[top + 2], p4 = topArr[top + 3];

src/codecs/avif.ts

@@ -421,7 +421,7 @@ function toRgba(y: Yuv, alpha: Yuv | null, toneMapping: ToneMapping, premultipli
         tableY[i] = (i - biasY) / rangeY;
         tableUV[i] = identity ? tableY[i] : (i - biasUV) / rangeUV;
     }
-    let out = new Uint8Array(width * height * 4);
+    let out: Uint8Array = new Uint8Array(width * height * 4);
     // HDR (PQ, HLG): the non-linear RGB values, converted to linear light and tone mapped after
     const hdr = y.transfer === TRANSFER_PQ || y.transfer === TRANSFER_HLG;
     const rgb = hdr ? new Float32Array(width * height * 3) : null;