Revert /app/target binary fallback in entrypoint

Superseded: the running fleet was created by `new project` (no /app
mount), and the one-way upgrade path now replaces the binary at its
canonical install location (/opt/huskies/bin/huskies) directly, so the
entrypoint needs no fallback logic.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019fHdm92yjvguPi2LiXfLB9

docker/entrypoint.sh

@@ -75,12 +75,4 @@ if [ -d /workspace/frontend ] && [ -f /workspace/frontend/package.json ]; then
     cd /workspace
 fi
 
-# If a rebuilt binary exists (from rebuild_and_restart or upgrade), prefer it
-# over the image-baked /usr/local/bin/huskies.
-REBUILT="/app/target/release/huskies"
-if [ -x "$REBUILT" ] && [ "$1" = "huskies" ]; then
-    shift
-    exec "$REBUILT" "$@"
-fi
-
 exec "$@"