refactor(cli): migrate argument parsing from Click to Cyclopts

[noirbizarre]

Part 1 of 3 of the CLI modernisation, split out of #1894 as requested for easier review.

This migrates command-line argument parsing from Click to Cyclopts, while keeping the existing command syntax, flags and behaviour. Output styling still goes through the pluggable pyinfra.api.output layer wired to Click (set_formatter(click.style) / set_echo(click.echo)), so this change is scoped to parsing only — Rich output arrives in the next PR.

• cli.py becomes a Cyclopts App with @app.default and typed Annotated parameters; PYINFRA_YES keeps its lenient boolean parsing (empty / on / off).
• --support is now a Cyclopts command; the previously duplicated support parameter and its unreachable handler are removed.
• main.py invokes the Cyclopts app and surfaces click.ClickException (CliError etc.) via their .show() / exit code.
• The confirmation prompt and all human output remain Click-based.
• pyproject: add cyclopts, keep click (now used for output only).
• Tests invoke the Cyclopts app through the updated run_cli helper.

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📚 Stacked PR series

This is one of three PRs that split the combined CLI refactor (originally #1894) into reviewable layers. They are stacked and land in order; Parts 2 & 3 stay in draft until the preceding part is merged.

• refactor(cli): migrate argument parsing from Click to Cyclopts #1901 — Part 1 — Click → Cyclopts argument parsing ← this PR
• feat(cli): Rich-based output, prints and debug-inventory #1902 — Part 2 — Rich-based output, prints & debug-inventory
• feat(cli): live hierarchical progress tree and informative error handling #1903 — Part 3 — live progress tree, TTY fixes & syntax-highlighted diffs

Original combined PR (kept for reference/discussion): #1894

Related issue: #785 (use Rich) — referenced, not closed.

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🎥 Showcase

Those are here to show what visually changed and what did not (yet).

In this PR, click is still in charge of rendering/styling, rich is not yet introduced.

Help

Inventory

Success

Error and diff

Multiline output

[Fizzadar]

Couple of tweaks then we're good to go I think!

[noirbizarre]

All comments addressed. 👍🏼

The version is now iso to the current format:

(Good to know for #1753, I love pathlib!)

[wowi42]

Re-reviewed after the requested changes. Approving.

Verified locally on this branch (Python 3.13):

• pyinfra --version prints pyinfra: v... again (matches the old Click output).
• pyinfra --support works and exits 0.
• -vvv bundling still works for verbosity.
• Missing operations exits 1 with a clear usage message (Click exited 2 with a usage error; the new message is more helpful, fine by me).
• Unknown option exits 1 (was 2 under Click; acceptable).
• PYINFRA_YES=off lenient parsing works.
• Full unit suite passes (1951 passed), ruff and mypy clean.

Two cosmetic Cyclopts differences in --help, not blockers:

• Flags now show [default: False] and repeatable options show [default: ()], which adds noise Click did not have. If Cyclopts has a flag to hide defaults for these, worth using in Part 2 or 3.
• The usage line reads pyinfra COMMAND [OPTIONS] INVENTORY [ARGS...]; the COMMAND token is a bit misleading for the default command.

The scripts/pyinfra-complete.{sh,zsh} removal is a breaking change for anyone sourcing those files, but it was requested in the earlier review and --install-completion (which also adds fish support) is a good replacement.