vNext: Pin Ruff to 0.17.0 and fix the import it flags

[RobHofmann]

Problem

Lint has failed on every push and PR to 5.0-dev since #547:

I001 [*] Import block is un-sorted or un-formatted
  --> custom_components/gree_custom/const.py:3:1

None of #547, #548 or #549 touched const.py.

Cause

lint.yml installed ruff>=0.16.3. Ruff 0.17.0 came out on 2026-10-09, so CI used 0.17.0 from that day on. The last green run (#546) used 0.16.10.

0.17 sorts an import with a trailing pragma comment differently. Ruff 0.16.10 and 0.17.0 want opposite forms of the same import, so no code passes both.

Change

• const.py: apply the 0.17 fix (ruff check --fix).
• lint.yml and requirements_dev.txt: pin Ruff to 0.17.0, so a new Ruff release cannot break CI again. A future bump goes in its own PR.
• docs/development.md: explain the pin.

Testing

• Ruff 0.17.0: ruff check . passes, ruff format --check . passes (72 files).
• Ruff 0.16.10 on the same tree reports the opposite I001 finding, which shows why the pin is needed.
• No behaviour change, so no harness or device test.

Notes

Contributors with an older local Ruff, or the VS Code Ruff extension with its bundled Ruff, see I001 the other way round. pip install -r requirements_dev.txt fixes that.