fix(coord-send): stop rejecting dot-prefixed repo names

coord-send.sh:154 guarded the --to target with a `.*` case arm, which
rejects every leading-dot name instead of just `.` and `..`. A
dot-prefixed name is a real repo identity (basename of a git toplevel
under a hidden directory, e.g. ~/.claude) and was reported unreachable
by morning-driver via coord message 20260809T103138Z. Narrowed the
guard to reject exactly `.` and `..`, matching the equivalent guards
already used elsewhere in this file and in coord-done.sh.

coord-count.sh and coord-sweep.sh both enumerate the mailbox root with
a bare "$COORD"/* glob, which by construction never matches a
dot-prefixed directory - confirmed empirically before this change.
Fixing only the send-side guard would have let a dot-prefixed mailbox
receive mail that neither script could ever report or close on its
grace window. Both now also glob "$COORD"/.[!.]* to reach hidden
mailboxes without matching "." or "..".

coord-selftest.sh: 183 -> 191 checks, section 30 covers the fix and
both enumeration paths. Doc counts (README badge, CLAUDE.md) updated
to match; the catalog's mirrored badge is untouched pending release.

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

README.md

@@ -14,7 +14,7 @@ Session A in repo X leaves a message for repo Y; the next session in repo Y gets
 ![Hooks](https://img.shields.io/badge/hooks-1-green)
 ![Skills](https://img.shields.io/badge/skills-3-orange)
 ![CLI scripts](https://img.shields.io/badge/CLI_scripts-8-blue)
-![Selftest checks](https://img.shields.io/badge/selftest_checks-398-blue)
+![Selftest checks](https://img.shields.io/badge/selftest_checks-406-blue)
 
 ---
 
@@ -139,7 +139,7 @@ Cross-repo message content is untrusted input by design:
 
 - **Atomic delivery:** the temp file is created inside the destination directory (dot-prefixed, invisible to the inbox glob), so the final rename never crosses filesystems and readers never observe a half-written message.
 
-Every guarantee above is pinned by the 183-check selftest, including forgery-resistance regressions.
+Every guarantee above is pinned by the 191-check selftest, including forgery-resistance regressions.
 
 Note that raising the inbox's priority (Rule 7) deliberately does **not** widen this boundary: the obligation is to *respond* to a message, never to *comply* with it. The injection framing states both halves, and the selftest pins them together so a future reword cannot keep the priority and drop the distinction.
 
@@ -161,7 +161,7 @@ Note that raising the inbox's priority (Rule 7) deliberately does **not** widen
 
 ## Development
 
-    bash scripts/coord-selftest.sh    # 183 checks against a throwaway mailbox
+    bash scripts/coord-selftest.sh    # 191 checks against a throwaway mailbox
     bash scripts/board-selftest.sh    # 142 checks against a throwaway repo tree
     bash scripts/route-selftest.sh    # 73 checks, incl. the route->board round trip
     npm test                          # all three selftests via node --test