v1.7.0 — transcript-only mode + guided help

New lean --transcript-only mode: fetch and output just the raw transcript — no metadata, description, chapters, comments, screenshots, or summary. It runs the Python script directly (no subagent), since a subagent would only relay the raw transcript back into context and pay its token cost twice. It also skips the heavy yt-dlp --dump-json metadata call entirely, naming the output folder by the video ID parsed from the URL.

Plus: a no-URL invocation now always answers with a guided text message instead of failing.

Highlights

• --transcript-only — raw transcript only, fast; no subagent; folder/file named by video ID. Combinable with --no-save. Multi-URL supported (no synthesis — it's raw data). The post-run "What next?" offers an in-context summary, so "transcript then summarize" needs no separate mode.
• No-URL guard — /yt-extract with no URL (and without --check) prints the full guided help when no flags were given, or a short flag-preserving "paste a URL" message when flags were passed. Plain text only — never an AskUserQuestion — so it stays safe in programmatic skill-to-skill calls.
• extract_video_id() — parses the 11-char ID from watch?v=, youtu.be/, /shorts/, /embed/, and /live/ URL forms.

The happy path is unchanged: /yt-extract <url> still runs the default structured summary immediately.

See CHANGELOG.md for full details.