[Bug]: --publish-socket rejects host paths that contain a colon

[thebenmerlin]

I have done the following

• I have searched the existing issues
• If possible, I've reproduced the issue using the 'main' branch of this project

Steps to reproduce

--publish-socket takes host_path:container_path. If the host path itself
contains a colon, parsing fails.

container run --publish-socket "/tmp/backup-2026-08-18T10:30:00.sock:/var/run/app.sock" alpine sleep 100

Current output:

Error: invalid publish-socket format /tmp/backup-2026-08-18T10:30:00.sock:/var/run/app.sock. Expected: host_path:container_path

Problem description

The host path in --publish-socket can legitimately contain a colon (for
example a timestamped filename), but the parser splits the argument on
every ':' and only accepts exactly 2 parts. Any host path with more than
one colon is rejected as an "invalid publish-socket format", even though
it's a valid path.

The fix should split on the last colon instead of every colon. The
container-side path is always a plain absolute path, so the last colon is
always the correct split point.

This is the same class of bug already fixed for container cp in #1969 /
#1970 (paths split on every colon instead of the first one), just not
applied to --publish-socket.

Parsing lives in Parser.publishSocket in
Sources/Services/ContainerAPIService/Client/Parser.swift.

Environment

- OS: macOS 26.5.1 (25F80)
- Xcode: Command Line Tools 26.2.0 
- Container: main branch (built from source)

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