Local dev stack improvements

- Extend docker-compose.dev.yml with optional monitoring profile
  (Prometheus, Grafana, Loki) via --profile monitoring
- Align dev PostgreSQL with production: pg_stat_statements + init scripts
- Add scripts/seed.ts with idempotent Berlin test data (user, route, activity)
- Add pnpm db:seed and pnpm dev:reset scripts
- Simplify CI e2e job: replace manual docker run + BRouter setup with
  docker compose up --wait; add db:seed step
- Improve scripts/dev.sh: Docker check, --wait health checks, --monitoring
  flag, seed step
- Add scripts/reset-dev.sh to wipe and restart the local stack
- Add .env.development.example with documented local defaults

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.env.development.example

@@ -0,0 +1,10 @@
+# Root-level local dev defaults.
+# Copy to `.env.development` (gitignored) to override.
+# All values here work out of the box — no changes needed for standard local dev.
+
+DATABASE_URL=postgres://trails:trails@localhost:5432/trails
+BROUTER_URL=http://localhost:17777
+
+# Change these for any environment that is not purely local.
+JWT_SECRET=dev-secret-not-for-production
+SESSION_SECRET=dev-secret-not-for-production