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

CHANGELOG.md

@@ -5,6 +5,27 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.20.3] - 2026-08-09
+
+### Fixed
+
+- **`coord-send.sh` rejected every dot-prefixed repo name, not just `.` and
+  `..`.** The `--to` guard used a `.*` case arm, so a real repo identity that
+  happens to be a hidden directory (basename of a git toplevel, e.g.
+  `~/.claude`) could never be addressed. Reported by morning-driver via
+  coord message. Narrowed to reject exactly `.` and `..`, matching the
+  equivalent guards already used elsewhere in `coord-send.sh` and in
+  `coord-done.sh`.
+- **`coord-count.sh` and `coord-sweep.sh` could not see a dot-prefixed
+  mailbox either.** Both enumerate the mailbox root with a bare `"$COORD"/*`
+  glob, which by construction never matches a dot-prefixed directory
+  (confirmed empirically before the fix). Fixing only the send-side guard
+  would have let a dot-prefixed mailbox receive mail neither script could
+  ever report or close on its grace window. Both now also glob
+  `"$COORD"/.[!.]*`.
+
+`coord-selftest.sh`: 183 -> 191 checks.
+
 ## [0.20.2] - 2026-08-03
 
 ### Added