chore(release): prepare v0.18.0 - version bump, and the entry point --focus was missing

release-plugin.mjs does not bump these; it REFUSES to release until they
already match the target (release-plugin.mjs:64). The bump belongs in this
repo, not in the catalog session, so the catalog step is now unblocked:
plugin.json, package.json, README badge and all three SKILL.md frontmatters
move to 0.18.0 together, and CHANGELOG's [Unreleased] becomes [0.18.0].

More important than the numbers: --focus was reachable by nobody. The board
SKILL.md is the operator's only entry point and it documented only --plan, so
"fokusdag pa X" would have routed to an unfocused plan on a released 0.18.0.
The skill now passes the user's phrasing through VERBATIM - resolving prose to
a slug in the skill would put a guess in front of a deterministic lookup, and
fokus= already reports what the phrase resolved to. It also relays the three
disclosure lines rather than trimming them as noise, since this is the one
rendering that hides repos.

check-versions: 0 ERROR, 1 WARN (catalog ref lags plugin.json - the documented
transient state before the ref bump).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0186vKCzuUEN5WcJB82kddzF

.claude-plugin/plugin.json

@@ -1,6 +1,6 @@
 {
   "name": "repo-mailbox",
-  "version": "0.17.0",
+  "version": "0.18.0",
   "description": "Local mailbox for coordination between Claude Code sessions in different repositories. Directed messages and broadcasts as plain Markdown files on your own disk, injected as context at session start. Local, private, no network.",
   "author": {
     "name": "Kjell Tore Guttormsen"