Allow --hostname as an alias for --host

[rolandwalker]

Description

Allow --hostname as an alias for --host, like #1721 for --username.

Checklist

• I added this contribution to the changelog.md file.
• I added my name to the AUTHORS file (or it's already there).
• To lint and format the code, I ran

  uv run ruff check && uv run ruff format && uv run mypy --install-types .

[github-actions]

No correctness/security regressions found in this PR’s delta.

• Change in mycli/main.py:1919 is a safe CLI alias addition (--hostname mapped to host) and does not alter connection logic.
• Added test in test/test_main.py:1488 covers the new alias path.

Residual risk / test gap:

• I couldn’t execute tests locally because pytest is not installed in this environment, so runtime validation is pending.
• Optional extra coverage: add a help-text assertion that both --host and --hostname are accepted/documented (to guard clickdc option-generation behavior changes).