Add Enigma2/OpenWebif M3U support: program mapping and zap-before-streaming

- Parse #EXTVLCOPT:program=N from M3U playlists (both full and streaming
  parsers, per channel, strict mode) and store it on playlist items
- Transcode multi-program MPEG-TS streams by mapping only the selected
  program's first video and audio stream (DVB teletext/subtitles in the
  program otherwise make FFmpeg fail to produce HLS)
- Optional per-source "zap before streaming" with configurable delay:
  POST /api/openwebif/zap takes sourceId + streamId, requires an enabled,
  zap-enabled M3U source containing that channel, derives the receiver
  from the configured source URL (never from the client), validates the
  Enigma2 service reference, uses a timeout without redirects and does
  not echo the receiver response
- Live TV: Stop button, and stop playback when leaving the page
- Tests for ordinary and program-tagged playlists and the zap endpoint

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test/m3u-parser.test.js

@@ -0,0 +1,70 @@
+const test = require('node:test');
+const assert = require('node:assert/strict');
+const { Readable } = require('node:stream');
+const { parse, parseStreaming } = require('../server/services/m3uParser');
+
+const ORDINARY = [
+    '#EXTM3U',
+    '#EXTINF:-1 tvg-id="news.one" group-title="News",News One',
+    'http://provider.test/news1.ts',
+    '#EXTINF:-1 group-title="Sports",Sports One',
+    'http://provider.test/sports1.ts',
+    ''
+].join('\n');
+
+// Enigma2/OpenWebif bouquet export: program tags, no group-title
+const PROGRAM_TAGGED = [
+    '#EXTM3U',
+    '#EXTVLCOPT:http-reconnect=true',
+    '#EXTINF:-1 tvg-id="1:0:1:65:65:53:CE40000:0:0:0:",RTP1',
+    '#EXTVLCOPT:program=101',
+    'http://receiver.test:8001/1:0:1:65:65:53:CE40000:0:0:0:',
+    '#EXTINF:-1 tvg-id="1:0:1:66:65:53:CE40000:0:0:0:",RTP2',
+    '#EXTVLCOPT:program=102',
+    'http://receiver.test:8001/1:0:1:66:65:53:CE40000:0:0:0:',
+    '#EXTINF:-1 tvg-id="untagged",Untagged',
+    'http://receiver.test:8001/untagged',
+    ''
+].join('\n');
+
+async function collect(input, batchSize) {
+    const batches = [];
+    for await (const batch of parseStreaming(input, batchSize)) batches.push(batch);
+    return batches;
+}
+
+for (const [label, toInput] of [['string', text => text], ['stream', text => Readable.from([text])]]) {
+    test(`streaming parser imports ordinary playlists without program tags (${label} input)`, async () => {
+        const batches = await collect(toInput(ORDINARY));
+        const channels = batches.flatMap(batch => batch.channels);
+        assert.equal(batches.at(-1).isLast, true);
+        assert.deepEqual(channels.map(c => [c.name, c.groupTitle, c.url, c.program]), [
+            ['News One', 'News', 'http://provider.test/news1.ts', null],
+            ['Sports One', 'Sports', 'http://provider.test/sports1.ts', null]
+        ]);
+        assert.deepEqual([...batches.at(-1).groups], ['News', 'Sports']);
+    });
+
+    test(`streaming parser keeps program tags per channel (${label} input)`, async () => {
+        const channels = (await collect(toInput(PROGRAM_TAGGED))).flatMap(batch => batch.channels);
+        assert.deepEqual(channels.map(c => [c.name, c.groupTitle, c.program]), [
+            ['RTP1', 'Uncategorized', '101'],
+            ['RTP2', 'Uncategorized', '102'],
+            ['Untagged', 'Uncategorized', null]
+        ]);
+    });
+}
+
+test('streaming parser does not leak program state between batches or into globals', async () => {
+    const batches = await collect(PROGRAM_TAGGED, 1);
+    assert.deepEqual(batches.filter(b => b.channels.length).map(b => b.channels[0].program), ['101', '102', null]);
+    assert.equal('currentVlcProgram' in globalThis, false);
+});
+
+test('full parser matches the streaming parser for ordinary and program-tagged playlists', async () => {
+    for (const playlist of [ORDINARY, PROGRAM_TAGGED]) {
+        const { channels } = await parse(playlist);
+        const streamed = (await collect(playlist)).flatMap(batch => batch.channels);
+        assert.deepEqual(channels, streamed);
+    }
+});