fix(compose): support the entrypoint field in service definitions

[itxtoledo]

Summary

Docker Compose's entrypoint: field was entirely ignored: ComposeService never parsed it, so any service relying on an entrypoint (e.g. entrypoint: ["/bin/sh", "-c"]) either launched with a mangled argv or failed to start with failed to find target executable ....

Apple's container CLI only accepts a single executable via --entrypoint <cmd> — a value with spaces like /bin/sh -c is treated as one executable path and fails to launch. This PR makes mocker mirror Docker's exec model (ENTRYPOINT [...] + CMD [...] concatenation) within that constraint.

Changes

• ComposeFile: parse entrypoint: (list and shell/string form), include it in multi-file merge and in the config hash so containers are recreated when it changes.
• ComposeOrchestrator: new pure helper resolveExec(entrypoint:command:) — the first entrypoint element becomes the --entrypoint executable and remaining elements are spliced ahead of the command argv.
• run / create / compose run: --entrypoint values are now split on spaces (Docker shell-form semantics) and routed through the same helper, so mocker run --entrypoint "/bin/sh -c" works.
• Tests: parsing (list + string + merge + hash) and resolveExec unit tests. Full suite: 453 tests pass.

Verification

Built locally and ran:

services:
  ep:
    image: alpine:latest
    entrypoint: ["/bin/sh", "-c"]
    command: ["echo COMPOSE_ENTRYPOINT_FIXED; sleep 300"]

mocker compose up -d + logs → COMPOSE_ENTRYPOINT_FIXED, container stays up. mocker run --entrypoint "/bin/sh -c" alpine echo RUN_EP_FLAG_FIXED → works (previously errored).

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