fix: bundled dust cleanup — lib/matrix_listener.sh (#264)

- Remove dead ROOM_ENCODED and EVENT_ID variables from matrix_listener.sh
  (were suppressed with SC2034 instead of removed)
- Remove dead REPO variable from dev-poll.sh and review-poll.sh
- Update header comment in matrix_listener.sh to list all 5 reply-routing
  cases (supervisor, gardener, dev, review, vault, action)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

review/review-poll.sh

@@ -12,9 +12,6 @@ export PROJECT_TOML="${1:-}"
 source "$(dirname "$0")/../lib/env.sh"
 source "$(dirname "$0")/../lib/ci-helpers.sh"
 
-
-# shellcheck disable=SC2034
-REPO="${CODEBERG_REPO}"
 # shellcheck disable=SC2034
 REPO_ROOT="${PROJECT_REPO_ROOT}"
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"