feat(install): add a one-line curl|bash installer

run.sh autodetects Ubuntu/Debian, Fedora/RHEL, Arch, and WSL; ensures git and
Docker; clones, builds, picks free ports (Caddy prefers 443, Postgres 5432),
generates a .env with a JWT secret and Postgres password, asks how many nodes to
run, and starts the stack. The node count persists via an auto-loaded
compose.override.yaml, so a later plain `docker compose up -d` keeps it; a fresh
clone with no override still starts all 10. Ignores the generated override.

.gitignore

@@ -9,6 +9,11 @@ build/
 .venv/
 venv/
 .env
+# Local compose overrides (e.g. run.sh's node-count limiter, bootstrap output)
+compose.override.yaml
+compose.override.yml
+docker-compose.override.yaml
+docker-compose.override.yml
 *.so
 .mypy_cache/
 .ruff_cache/