fix(moq-hls): account for audio groups in master variants

[kixelated]

Summary

• Add the maximum selectable audio bitrate to each video variant's BANDWIDTH.
• Split audio renditions into homogeneous codec groups and emit one accurate video variant per group.
• Cover combined bandwidth and mixed AAC/Opus groups with regression tests.

The root cause was that master rendering treated a video rendition as the complete playable HLS variant. It therefore advertised only the video bitrate and copied the first audio codec even though the referenced audio group could select other renditions.

Closes #2250.

Public API changes

• None. The master-playlist renderer is private to moq-hls.
• Cross-package synchronization is not applicable because this does not change the MoQ wire protocol, catalog format, or public API.

Test plan

• cargo test -p moq-hls (24 passed)
• cargo clippy -p moq-hls --lib -- -D warnings
• cargo fmt --all -- --check
• git diff --check

(Written by GPT-5)

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Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 08f9ae9c-763c-4f6a-b2a7-0070d5a0554c

📥 Commits

Reviewing files that changed from the base of the PR and between 11f4c37 and d2a109d.

📒 Files selected for processing (1)

• rs/moq-hls/src/export/master.rs

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Walkthrough

HLS master playlist generation now groups audio renditions by codec, assigns codec-specific group IDs when needed, and calculates group bandwidths. Video stream entries are rendered per audio group with matching CODECS, AUDIO, and combined bandwidth attributes. Audio-only playlists continue to emit stream entries for each audio rendition. Tests cover multi-codec group IDs and video stream attributes.

✨ Finishing Touches

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch codex/fix-hls-master-variants

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