feat(network): request-throttle controls to avoid YouTube rate-limiting

Re-implements the sleepRequests/sleepInterval/maxSleepInterval feature
(--sleep-requests / --sleep-interval / --max-sleep-interval) from the
stale feat/binary-management-and-library-scale branch, ported onto
current main's structure (zod settingsSchema, decomposed NetworkCard).
All default to 0/off, preserving current behaviour.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/main/core/buildArgs.ts

@@ -102,6 +102,12 @@ export interface AccessOptions {
   proxy: string
   /** yt-dlp --limit-rate value, e.g. '2M'; empty means unlimited */
   rateLimit: string
+  /** `--sleep-requests` seconds (pause between extraction requests); 0/omitted = off */
+  sleepRequests?: number
+  /** `--sleep-interval` seconds (min pause before each download); 0/omitted = off */
+  sleepInterval?: number
+  /** `--max-sleep-interval` seconds (max of the random pre-download pause); applies only with a non-zero sleepInterval */
+  maxSleepInterval?: number
   /** absolute path to aria2c.exe; omit to use yt-dlp's built-in downloader */
   aria2cPath?: string
   /** aria2c parallel connections (-x/-s), clamped to 1–16; omitted = 16 (L64) */
@@ -323,6 +329,19 @@ function accessArgs(a: AccessOptions): string[] {
   const args: string[] = []
   if (a.proxy.trim()) args.push('--proxy', a.proxy.trim())
   if (a.rateLimit.trim()) args.push('--limit-rate', a.rateLimit.trim())
+  // Request throttle — the antidote to YouTube's rate-limit/403 wall on big
+  // channel pulls. `--sleep-requests` spaces out the extraction requests; the
+  // sleep-interval pair brackets a random pause before each download. yt-dlp
+  // requires --sleep-interval to be present for --max-sleep-interval to be
+  // meaningful, and a max below the min is nonsensical, so max is gated on both.
+  const sleepRequests = a.sleepRequests ?? 0
+  if (sleepRequests > 0) args.push('--sleep-requests', String(sleepRequests))
+  const sleepInterval = a.sleepInterval ?? 0
+  if (sleepInterval > 0) {
+    args.push('--sleep-interval', String(sleepInterval))
+    const maxSleep = a.maxSleepInterval ?? 0
+    if (maxSleep > sleepInterval) args.push('--max-sleep-interval', String(maxSleep))
+  }
   if (a.aria2cPath) {
     args.push('--downloader', a.aria2cPath, '--downloader-args', aria2cArgs(a.aria2cConnections))
   }

src/main/download.ts

@@ -222,6 +222,9 @@ export function buildCommand(opts: StartDownloadOptions, cookiesFile?: string):
   const access = {
     proxy: settings.proxy,
     rateLimit: settings.rateLimit,
+    sleepRequests: settings.sleepRequests,
+    sleepInterval: settings.sleepInterval,
+    maxSleepInterval: settings.maxSleepInterval,
     aria2cPath,
     aria2cConnections: settings.aria2cConnections,
     // L136/M6: incognito attaches no cookies from the browser either.

src/main/settingsSchema.ts

@@ -94,6 +94,10 @@ export const SETTINGS_FIELD_SCHEMAS: { [K in keyof Settings]: z.ZodType<Settings
   defaultVideoQuality: z.enum(VIDEO_QUALITY_OPTIONS),
   defaultAudioQuality: z.enum(AUDIO_QUALITY_OPTIONS),
   rateLimit: trimmedWhere((v) => RATE_LIMIT_RE.test(v)),
+  // Throttle seconds (0–300, 0 = off) to dodge YouTube's rate-limit/403 wall.
+  sleepRequests: clampedInt(0, 300),
+  sleepInterval: clampedInt(0, 300),
+  maxSleepInterval: clampedInt(0, 300),
   // Power-user field; yt-dlp's client list evolves. Accept any trimmed string.
   youtubePlayerClient: z.string().transform((v) => v.trim()),
   // Credential-bearing fields — settings.ts encrypts these AFTER parsing.