chore(release): 0.24.0

Version bump across the six files the release gate checks (plugin.json,
package.json, README badge, three SKILL.md frontmatter fields) plus the
CHANGELOG entry, covering the three commits unreleased since v0.23.0:

- 09fd4b7 feat(board): --inbox-plan, a fourth rendering
- 44fb34a fix(hooks): state-line-guard MAX_LINES 60 -> 120
- 19c0c10 feat(coord,board): dead-letter detection (WP1d detection half)

All four selftest suites green at this commit: coord 197/197, board
178/178, route 69/69, state-line-guard 21/21.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Neu6DivA9k5op2rSEvcewn

skills/board/SKILL.md

@@ -20,7 +20,7 @@ description: >-
   user names no repo and no tool — choosing *between* repos is this skill. Not for
   "where were we" inside the current repo: that is this repo's own STATE.md,
   already injected at session start.
-version: "0.23.0"
+version: "0.24.0"
 ---
 
 # board — which repo deserves the next session

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   broadcast", "that announcement is outdated, pull it", "trekk tilbake kringkastingen",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: "0.23.0"
+version: "0.24.0"
 ---
 
 # coord-send — natural-language front door for inter-repo messages

skills/route/SKILL.md

@@ -14,7 +14,7 @@ description: >-
   the operator names no model and no tool — choosing the model for the next
   session IS this skill. Not for choosing which REPO gets the next session:
   that is the `board` skill.
-version: "0.23.0"
+version: "0.24.0"
 ---
 
 # route — what the next session should run with