feat(tool-youtube-transcript): YouTube transcription tool

New standard tool extension backed by a self-hosted transcriber service
(http://100.102.55.49:41090, Tailscale, no API key). One tool
youtube_transcript — fetches transcripts for YouTube videos. Returns
completed (full text + timestamped segments), queued/processing (position
+ ETA + .youtube_subtitles_pending retry convention), or failed (error).

Pure core: validateUrl + format* functions + truncateOutput. Injected
edge: TranscriptClient (injectable fetchFn, AbortSignal.any for
cancellation). concurrencySafe true, capabilities network. 30 tests.

Verified: tsc EXIT 0, 1152 vitest, biome clean (327 files). Boot smoke
clean.

1 files changed, 10 insertions, 0 deletions

diff --git a/bun.lock b/bun.lock
index bf424a1..3d66f23 100644
--- a/bun.lock
+++ b/bun.lock
@@ -76,6 +76,7 @@
         "@dispatch/tool-shell": "workspace:*",
         "@dispatch/tool-web-search": "workspace:*",
         "@dispatch/tool-write-file": "workspace:*",
+        "@dispatch/tool-youtube-transcript": "workspace:*",
         "@dispatch/transport-http": "workspace:*",
         "@dispatch/transport-ws": "workspace:*",
       },
@@ -238,6 +239,13 @@
         "@dispatch/kernel": "workspace:*",
       },
     },
+    "packages/tool-youtube-transcript": {
+      "name": "@dispatch/tool-youtube-transcript",
+      "version": "0.0.0",
+      "dependencies": {
+        "@dispatch/kernel": "workspace:*",
+      },
+    },
     "packages/trace-replay": {
       "name": "@dispatch/trace-replay",
       "version": "0.0.0",
@@ -362,6 +370,8 @@
 
     "@dispatch/tool-write-file": ["@dispatch/tool-write-file@workspace:packages/tool-write-file"],
 
+    "@dispatch/tool-youtube-transcript": ["@dispatch/tool-youtube-transcript@workspace:packages/tool-youtube-transcript"],
+
     "@dispatch/trace-replay": ["@dispatch/trace-replay@workspace:packages/trace-replay"],
 
     "@dispatch/trace-store": ["@dispatch/trace-store@workspace:packages/trace-store"],