style: address Copilot review feedback

- Clarify comment: random number range is [0, totalWeight) exclusive
- Rename test: "fair distribution" → "be able to select both" (we test
  reachability, not statistical distribution)

Author: PascalThuet

src/streaming/utils/baseUrlResolution/DVBSelector.js

@@ -110,7 +110,7 @@ function DVBSelector(config) {
                     cumulWeights.push(totalWeight);
                 });
 
-                // pick a random number between zero and totalWeight
+                // pick a random number between zero (inclusive) and totalWeight (exclusive)
                 rn = Math.floor(Math.random() * totalWeight);
 
                 // select the index for the range rn falls within

test/unit/test/streaming/streaming.utils.DVBSelector.js

@@ -158,7 +158,7 @@ describe('BaseURLResolution/DVBSelector', function () {
         stub.restore();
     });
 
-    it('should select all equal-weight baseUrls with fair distribution (RFC 2782)', () => {
+    it('should be able to select both equal-weight baseUrls (RFC 2782)', () => {
         const baseUrls = [
             { dvbPriority: 1, dvbWeight: 1, serviceLocation: 'cdn-a' },
             { dvbPriority: 1, dvbWeight: 1, serviceLocation: 'cdn-b' }