docs(catalog): re-measure repo-mailbox's badge-less stat axes at v0.18.0

Both numbers were measured at v0.12.x and never re-measured across six version
bumps. Neither axis carries a shields badge, so the badge-mirroring gate now
being designed would not have caught either — they are stated here as the
ungated class that still needs a human pass.

Measured today against repo-mailbox v0.18.0:
- CLI scripts 6 -> 8: scripts/ holds 11 *.sh, of which 3 are selftests
  (board, coord, route), leaving 8 operator-facing entry points.
- selftest checks 251 -> 374: coord 183 + route 73 + board 118, from running
  the three selftests (each sandboxes its mailbox via mktemp -d).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RDSiMcgLMpEETwtkc86Nym

README.md

@@ -188,7 +188,7 @@ A local mailbox for coordination between Claude Code sessions in different repos
 - **`board`** — read-only cross-repo attention board: which repos have a live next step, which are blocked and on whom, which owe a reply, and what each costs to move
 - **`route`** — turns four scored traits of the next task into a model/effort row from a closed six-row rubric, with a pasteable startup command and a one-row-cheaper fallback
 
-1 hook · 3 skills · 6 CLI scripts · 251 selftest checks · [Full documentation →](https://git.fromaitochitta.com/open/repo-mailbox)
+1 hook · 3 skills · 8 CLI scripts · 374 selftest checks · [Full documentation →](https://git.fromaitochitta.com/open/repo-mailbox)
 
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