tools/dev-deploy: long-lived dev environment behind host Caddy

A docker-compose stack that hosts postgres, redis, mailpit, backend,
gateway, and an app-routing Caddy. Reachable through the host Caddy at
https://www.galaxy.lan (static SPA) and https://api.galaxy.lan (REST +
gRPC). Coexists with tools/local-dev/ and tools/local-ci/ by giving
every name (compose project, container, network, volume) a distinct
galaxy-dev-* prefix.

State is persisted in named volumes; game-state lives under
${GALAXY_DEV_GAME_STATE_DIR:-$HOME/.galaxy-dev/game-state} so the
default works for a non-root runner without sudo.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tools/dev-deploy/.env.example

@@ -0,0 +1,21 @@
+# Defaults for the long-lived dev stack. Copy to `.env` and edit
+# per-environment overrides. Everything in this file is non-secret;
+# real credentials would go through Gitea Actions secrets and never
+# this file.
+#
+# The compose `${VAR:-default}` expansions fall back to the values
+# baked into `docker-compose.yml`, so this file documents the knobs
+# rather than driving them.
+
+# Auto-provisioned sandbox bootstrap. Empty disables the bootstrap.
+BACKEND_DEV_SANDBOX_EMAIL=dev@galaxy.lan
+BACKEND_DEV_SANDBOX_ENGINE_IMAGE=galaxy-engine:dev
+BACKEND_DEV_SANDBOX_ENGINE_VERSION=0.1.0
+BACKEND_DEV_SANDBOX_PLAYER_COUNT=20
+
+# `123456` short-circuits the email-code path for the dev account.
+# Leave empty in environments where real Mailpit codes must be used.
+BACKEND_AUTH_DEV_FIXED_CODE=123456
+
+# Name of the external Docker bridge the host Caddy is attached to.
+GALAXY_EDGE_NETWORK=edge