Release 0.1.0: MIT license, changelog, multi-arch Docker image without CLI builds

- LICENSE (MIT), CHANGELOG for 0.1.0, README overhaul
- docker-compose.release.yml pulling the registry image
- Dockerfile cross-compiles the server with cargo-zigbuild for amd64 and arm64;
  the terminal client is no longer built into the image
- Server, install script and settings point to a source install of the
  terminal client when no prebuilt binaries are available (/info: cli_builds)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.env.example

@@ -26,3 +26,9 @@ OPENROUTER_API_KEY=
 
 # Time zone for automations (cron schedules) and timestamps, e.g. Europe/Berlin
 TZ=UTC
+
+# Image version for docker-compose.release.yml (e.g. 0.1.0); default: latest
+CODECRAFT_VERSION=latest
+
+# Log format: empty for text, "json" for one JSON object per line
+CODECRAFT_LOG_FORMAT=