fix(up): allow entrypoint and command together, place --entrypoint before image

[Cyb3rDudu]

Compose files using entrypoint: ["/bin/bash","-c"] (or sh) plus a multi-line command: heredoc silently drop the command: part — the script never runs:

services:
  web:
    image: httpd:2.4
    entrypoint: ["/bin/bash", "-c"]
    command:
      - |
        sed -i "s|Listen 80|Listen 8080|" /usr/local/apache2/conf/httpd.conf
        exec httpd-foreground

Two bugs in ComposeUp.swift::configService:

1. entrypoint and command go through an else if, so setting both means command is dropped.
2. --entrypoint is appended after the image and gets every entrypoint element — but container run --entrypoint only takes one binary.

Fix pulls the translation into a static helper:

• First entrypoint element → --entrypoint <bin> (before the image)
• Rest of entrypoint + every command element → positional args after the image

Tests: 8 static cases for the helper covering all combinations (nil/empty/single/multi entrypoint × nil/command, including the bash-c heredoc shape from #77), plus one dynamic test that runs sh -c with a multi-line script and asserts the container is actually running afterward.

Fixes #77.