feat(youtube): extract transcript highlights like Reddit comment gems

Add extract_transcript_highlights() that scores sentences by specificity
(numbers, proper nouns, topic relevance) and filters YouTube filler
(subscribe, welcome back, etc). Top 5 highlights shown as structured
bullets in compact output. Full transcript moved to collapsible <details>
block so the LLM reads highlights first, full text on demand.

SKILL.md updated to instruct the judge agent to quote highlights
directly in synthesis, same as Reddit top comments.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/lib/render.py

@@ -257,8 +257,15 @@ def render_compact(report: schema.Report, limit: int = 15, missing_keys: str = "
             lines.append(f"**{item.id}** (score:{item.score}) {item.channel_name}{date_str}{eng_str}{_xref_tag(item)}")
             lines.append(f"  {item.title}")
             lines.append(f"  {item.url}")
+            if item.transcript_highlights:
+                lines.append("  Highlights:")
+                for hl in item.transcript_highlights[:5]:
+                    lines.append(f'    - "{hl}"')
             if item.transcript_snippet:
-                lines.append(f"  Transcript: {item.transcript_snippet}")
+                word_count = len(item.transcript_snippet.split())
+                lines.append(f"  <details><summary>Full transcript ({word_count} words)</summary>")
+                lines.append(f"  {item.transcript_snippet}")
+                lines.append("  </details>")
             lines.append(f"  *{item.why_relevant}*")
             lines.append("")