scripts: dev-start/dev-stop for local stack (backend+frontend)

dev-start.sh: starts node backend (better-sqlite3, :4001) + react frontend
(ws storage mode, :3999). Uses absolute DB_PATH to avoid workspace cwd
ambiguity (npm run server:dev runs in server/ subdir). Idempotent — skips
ports already in use.

dev-stop.sh: kills procs on :3999/:4001, sweeps node --watch + react-scripts.

Both write tmp/*.log + tmp/*.pid for debugging.

scripts/dev-stop.sh

@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+# Stop local dev stack. Usage: ./scripts/dev-stop.sh
+set -uo pipefail
+cd "$(dirname "$0")/.."
+
+stopped=0
+for port in 3999 4001; do
+  pids=$(lsof -ti :$port 2>/dev/null || true)
+  if [ -n "$pids" ]; then
+    echo "stopping :$port (pid: $pids)"
+    kill $pids 2>/dev/null || true
+    stopped=1
+  fi
+done
+
+# also kill recorded pids
+for f in tmp/server.pid tmp/fe.pid; do
+  if [ -f "$f" ]; then
+    pid=$(cat "$f")
+    kill "$pid" 2>/dev/null || true
+    rm -f "$f"
+  fi
+done
+
+# node --watch spawns children — sweep by port pattern
+pids=$(pgrep -f "node --watch index.js|react-scripts start" 2>/dev/null || true)
+if [ -n "$pids" ]; then
+  echo "sweeping node dev procs: $pids"
+  kill $pids 2>/dev/null || true
+fi
+
+if [ "$stopped" = "0" ]; then
+  echo "nothing running."
+fi
+echo "stopped."