docs: correct README facts and document CLI options

[lesnik512]

Summary

README facts that did not match the code, two small CLI fixes found alongside, and prose cleanup.

Changes

• profiles was listed under supported composition, but it is in IGNORED_SERVICE_KEYS (compose2pod/parsing.py:44-53) and only produces an "ignoring" warning (parsing.py:832-834); nothing else reads it, so every service runs regardless of profile. Moved it to a new "accepted and ignored with a warning" line with the other keys from that dict: ports, expose, restart, stdin_open, tty, stop_signal, stop_grace_period.
• pip install compose2pod[yaml] is a glob in zsh and fails. Quoted it in the README and in the missing-extra error (compose2pod/read.py:73); the CLI test now asserts the quoted form (written failing first).
• --pod-name and --format had no argparse help (compose2pod/cli.py:24-25). Added help strings (pod name is also the container name prefix, emit.py:154; auto tries JSON then YAML, read.py:91), with a test on --help output written failing first. The README now lists every CLI option.
• Requirements and conformance paragraphs shortened; ADR-0006 confirmed as the source for the 4.9 to 6.1 range.
• Bold-label bullets made plain, dashes removed from prose. Error strings untouched.

Checklist

• Lint and format pass (ruff)
• Type check passes (ty)
• Tests pass and new behavior is covered
• Build succeeds (uv build) if packaging or build config changed
• Repo metadata stays consistent across the three surfaces (GitHub description, pyproject description, profile blurb) if this touches packaging