Adds a Learnings entry for the 2026-04-30 slide-10 insert: documents
the styled-HTML approach chosen (no PNG asset existed for this dialog),
the slide-12 caption-strip pattern reuse, and a postmortem for the
sentinel-replacement collision where pre-resolving ##S10## to "11" before
running the n=11..48 loop double-incremented old-slide-10 to "12". Adds
two forward-looking rules: (1) use distinct sentinel prefixes or
single-pass resolution when mixing pre-resolved and loop-resolved slides,
and (2) check raw file content for literal apostrophes vs HTML entities
when pattern-matching comment strings.
Co-Authored-By: Claude <noreply@anthropic.com>