feat(docker): guided first run for the Compose deployment

A new Docker install was: clone (undocumented), copy .env.example by hand,
fix an Unraid data path and a Perth time zone, replace `changeme`, run the
start script, and then guess when the server was up. Start-Codeman.sh now
does all of it from a fresh clone:

- Preflight names the fix for a missing docker CLI, a missing or too-old
  Compose plugin (config --environment needs 2.27.2, docker/compose#11891),
  and an unreachable daemon (docker group, never sudo).
- With no docker/.env, it asks three questions (data folder, port,
  password; Enter takes each default: ~/codeman-docker, 3000 or the next
  free port, a generated password) and writes docker/.env FROM the example,
  so every key the updater's diffRequiredEnvKeys expects is present. Mode
  0600, host time zone, values Compose would interpolate single-quoted.
  Refuses $HOME, ~/.codeman (a native install's state dir) and anything
  inside the checkout (the image build context). --yes / no TTY take the
  defaults, --setup-only stops after writing the file. An existing .env is
  never edited, and root never runs the setup (Unraid keeps the hand route).
- After `up`, it waits until the server answers (docker exec probe, crash
  loop caught by the restart count) and prints the URL, the LAN URL, the
  generated password and the logs/stop commands; --no-wait skips the wait.
- `changeme` is refused before anything starts (the container publishes on
  every interface and holds the Docker socket); Update-Codeman.sh checks it
  before its build and down so the stack is never left stopped.
- Compose settings are read with ONE config --environment call, with its
  error reported, instead of three silent ones.

docker-compose.yaml and server.Dockerfile are untouched (their hashes gate
the in-app updater), and .env.example changes values and comments only.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

README.md

@@ -87,10 +87,17 @@ codeman users add alice --admin      # create the first admin account
 codeman web --multiuser              # named logins + per-user case spaces
 ```
 
-**Prefer Docker Compose?** A local-image Compose deployment ships in `docker/`: copy `docker/.env.example` to `docker/.env`, set `CODEMAN_PASSWORD`, then run `bash docker/Start-Codeman.sh` on Linux. Codeman runs in a container and spawns Docker cases as sibling containers through the host socket. After updating, run the script again rather than a plain `docker compose up`, so the rebuilt image, refreshed volumes and entrypoint arrive together. See the [Docker deployment guide](docker/README.md) for direct Compose commands, storage and networking options.
-
 Details in [Multi-User Mode](#multi-user-mode-opt-in) below.
 
+**Prefer Docker Compose?** Clone the repo and run one script (Linux, Docker with the Compose v2 plugin):
+
+```bash
+git clone https://github.com/Ark0N/Codeman.git && cd Codeman
+bash docker/Start-Codeman.sh
+```
+
+The first run asks three questions (data folder, port, password; Enter takes the default, including a generated password), writes `docker/.env` for you, builds the image and ends on the URL once Codeman answers. The image already includes Claude Code, Codex, Gemini CLI and OpenCode. Codeman runs in a container and spawns Docker cases as sibling containers through the host socket. To update, use **App Settings → Updates** or run the script again rather than a plain `docker compose up`, so the rebuilt image, refreshed volumes and entrypoint arrive together. See the [Docker deployment guide](docker/README.md) for Unraid, direct Compose commands, storage and networking options.
+
 <details>
 <summary><strong>Keep it running in the background</strong></summary>