feat(stream-test): persistent YouTube ad auto-skipper for the broadcast

Adds ad-skip.mjs: connects over CDP and injects a watcher into every tab
(current and future) that clicks "Skip ad" the moment it appears, closes overlay
ads, and fast-forwards unskippable ads (seek-to-end + 16x + mute) so they clear
in ~1s. Self-contained (no extension, no hosts/network changes) and reconnects
across Chrome restarts. Documented in the README.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

bot/scripts/stream-test/README.md

@@ -21,7 +21,13 @@ real browsing session captured from the X display.
 - `scenario.mjs` - the browse scenario (YouTube -> IU live -> 1080p ->
   fullscreen -> Naver -> 나무위키), driven with the human helpers. Connects to a
   Chrome already running with `--remote-debugging-port` (`CDP_PORT`, default
-  9222) on the streamed display.
+  9222) on the streamed display. Captions default OFF, auto-enabling a Korean
+  track when one exists.
+- `ad-skip.mjs` - persistent YouTube ad auto-skipper. Connects over CDP and
+  injects a watcher into every tab (current and future) that clicks "Skip ad"
+  the instant it appears, closes overlay ads, and fast-forwards unskippable ads
+  (seek-to-end + 16x + mute). Run it alongside the broadcast. Reconnects across
+  Chrome restarts.
 
 ## Run
 ```
@@ -30,6 +36,9 @@ bun bot/scripts/stream-test/stream-hold.ts
 
 # Chrome on the streamed display with remote debugging, then:
 node bot/scripts/stream-test/scenario.mjs
+
+# keep YouTube ads auto-skipped for the whole broadcast (separate process):
+node bot/scripts/stream-test/ad-skip.mjs
 ```
 
 Recommended Chrome flags on the streamed display (avoids the "restore pages?"