chore(release): prepare v0.20.3 - dot-prefixed repo name fix

Version bump for f425a11 (coord-send.sh/coord-count.sh/coord-sweep.sh
dot-prefixed repo name fix). Bumps plugin.json, package.json, README
badge, and the three skill frontmatters together; CHANGELOG entry added.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CHmf1VfCvaYXamJxe5y6Vt

skills/coord-send/SKILL.md

@@ -15,7 +15,7 @@ description: >-
   covers retiring a broadcast that has become wrong or obsolete: "retract that
   broadcast", "that announcement is outdated, pull it", "trekk tilbake kringkastingen",
   "den broadcasten er utdatert".
-version: "0.20.2"
+version: "0.20.3"
 ---
 
 # coord-send — natural-language front door for inter-repo messages