fix(m3u): support multiple URL lines under a single #EXTINF

[stackia]

Closes #740

Problem

An M3U entry written as one #EXTINF followed by several URL lines lost every URL except the first:

#EXTINF:-1 group-title="分组1",Channel 3
https://example.com/stream3$线路1
https://example.com/stream3$线路2

Both layers were affected:

• src/m3u.c: in_entry was reset after the first URL, so the second URL was silently dropped from the transformed /playlist.m3u and no service was created for it.
• web-ui/src/lib/m3u-parser.ts: currentExtinf was reset after the first URL, so the player parsed such an entry as a single-source channel.

Fix

• Server: keep the entry open after the first URL. Each additional URL-looking line (scheme://... or /path) under the same #EXTINF gets its own service path (.../Channel/label, or .../Channel/2, /3 when unlabelled). The transformed playlist preserves the input shape: the #EXTINF line is written once and the rewritten URLs follow it; entries that repeat #EXTINF stay repeated. The blank separator between entries is deferred until the next tag so single-URL output is byte-identical to before. catchup-source lives on the one #EXTINF line, so the catchup service is created and rewritten once (against the first source). Stray non-URL text after an entry is still ignored.
• Web UI: consecutive URL lines under one #EXTINF are appended as sources of the same channel.
• Docs (zh source + en translation): one #EXTINF followed by multiple URL lines is the documented way to declare a multi-source channel; the example output shows the converted playlist keeping that structure.

Tests

• New vitest cases for parseM3U (multi-URL entry, mixing with repeated #EXTINF, catchup propagation, orphan URL lines).
• New e2e class TestM3UMultiURLPerEXTINF in e2e/test_m3u.py: shape preserved with every URL rewritten, unlabelled URLs get unique paths, repeated-#EXTINF input stays repeated, catchup rewritten once for a multi-URL entry, stray text ignored.
• Full e2e suite (601 passed), pnpm run lint, tsc --noEmit, pnpm run web-ui:test, and pnpm run docs:build pass locally; all CI checks green.

Manual check

Web player against the fixed binary with the issue's playlist form: Channel 3 is listed once, its source menu shows 线路1 / 线路2, and an unlabelled three-URL entry shows Source 1 / Source 2 / Source 3.

  

[github-actions]

Documentation preview

The documentation preview has been deployed for this pull request.

• Preview: https://thankful-water-0a297bf00-746.eastasia.1.azurestaticapps.net
• Commit: f97ae8f

[cursor]

Bugbot couldn't run - usage limit reached

Bugbot is counted against Cursor usage for this user or team, and this run hit a usage or spend limit.

A user or team admin can review and increase usage limits in the Cursor dashboard.

(requestId: serverGenReqId_e53f5288-b28c-4425-8c03-5d0fb3ff2e6f)