feat: Tdarr Local Flow Plugin Suite v1.0

7 atomic plugins for automated x265 transcoding pipeline:
- utility/mediaAnalyzerGOP    : GOP calc, FPS detection, film/series/anime routing
- utility/setAnimationFlag    : manual animation flag override
- utility/extractChaptersXml  : mkvextract chapters to XML
- audio/audioSelectorClamping : codec scoring, clamped Opus bitrates, 2 outputs
- audio/backupSourceAudio     : lossless DTS/TrueHD ITA backup (-c:a copy)
- subtitles/extractSubtitlesAndOcr : SRT extract + SubtitleEdit OCR for PGS
- video/transcode2PassX265    : 2-pass x265, Lanczos 1080p bound, Opus mux

Test suite: 34 unit tests + 3 integration tests (FFmpeg real files)
FlowHelpers mock for local testing included
Docs: integration-guide.md with canvas wiring and deploy instructions

LocalFlowPlugins/audio/backupSourceAudio/1.0.0/index.js

@@ -0,0 +1,94 @@
+'use strict';
+
+const path = require('path');
+const fs   = require('fs');
+
+/* eslint-disable no-param-reassign */
+
+/**
+ * backupSourceAudio
+ * Extracts the original ITA audio track as a lossless bitstream copy,
+ * ONLY when the codec is DTS or TrueHD.
+ * Output is saved next to the source file (same directory).
+ */
+
+const BACKUP_CODECS = ['dts', 'truehd'];
+const details = () => ({
+  name: 'Backup Source Audio (DTS / TrueHD ITA)',
+  description:
+    'Extracts the ITA audio track as a lossless bitstream copy (-c:a copy) '
+    + 'when the source codec is DTS or TrueHD. '
+    + 'Output is saved next to the source file. '
+    + 'Silently skips if the ITA track does not require backup.',
+  style: { borderColor: '#F44336' },
+  tags: 'audio,backup',
+  isStartPlugin: false,
+  pType: '',
+  requiresVersion: '2.11.01',
+  sidebarPosition: -1,
+  icon: 'faSave',
+  inputs: [],
+  outputs: [
+    { number: 1, tooltip: 'Continue to next plugin' },
+  ],
+});
+
+const plugin = async (args) => {
+  const { jobLog, inputFileObj, variables, workDir } = args;
+
+  const inputFile = inputFileObj._id;
+  jobLog(`[backupSourceAudio] Processing: ${inputFile}\n`);
+
+  const hasIta     = variables.audioHasIta === 'true';
+  const itaCodec   = (variables.audioItaCodecName || '').toLowerCase();
+  const itaIdx     = variables.audioItaStreamIndex;
+
+  if (!hasIta) {
+    jobLog('[backupSourceAudio] No ITA track found — skipping.\n');
+    return { outputNumber: 1, outputFileObj: inputFileObj, variables };
+  }
+
+  const needsBackup = BACKUP_CODECS.some((c) => itaCodec.includes(c));
+  if (!needsBackup) {
+    jobLog(`[backupSourceAudio] ITA codec "${itaCodec}" does not require backup — skipping.\n`);
+    return { outputNumber: 1, outputFileObj: inputFileObj, variables };
+  }
+
+  // Determine output extension
+  let ext = '.dts';
+  if (itaCodec.includes('truehd')) ext = '.thd';
+
+  const sourceDir = path.dirname(inputFile);
+  const baseName  = path.basename(inputFile, path.extname(inputFile));
+  const outFile   = path.join(sourceDir, `${baseName}.ita${ext}`);
+
+  jobLog(`[backupSourceAudio] Backing up ITA ${itaCodec} -> ${outFile}\n`);
+
+  const { CLI } = require('../../../../FlowHelpers/1.0.0/cliUtils');
+  const cli = new CLI({
+    cli: args.ffmpegPath,
+    spawnArgs: [
+      '-y',
+      '-i', inputFile,
+      '-map', `0:${itaIdx}`,
+      '-c:a', 'copy',
+      outFile,
+    ],
+    WorkDir: workDir,
+    jobLog,
+  });
+
+  const { cliExitCode } = await cli.runCli();
+
+  if (cliExitCode !== 0) {
+    jobLog(`[backupSourceAudio] WARNING: FFmpeg exited with code ${cliExitCode}. Backup may be incomplete.\n`);
+  } else {
+    jobLog(`[backupSourceAudio] Backup complete: ${outFile}\n`);
+    variables.audioBackupPath = outFile;
+  }
+
+  return { outputNumber: 1, outputFileObj: inputFileObj, variables };
+};
+
+module.exports.details = details;
+module.exports.plugin = plugin;