docs: sweep em dashes out of the active published surface (#180)

Em dashes crept back into examples, docs/platform-native.md, several READMEs,
the ponytail-debt skill, and a command file since 88431de. Replaced with plain
punctuation (commas, matching the house convention), .openclaw mirror
regenerated. Follows 88431de's scope: leaves untouched the vendored caveman
SKILL.md and the dated benchmarks/results/ writeups (historical records).

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>