Add Python 3.14 support on Windows

[pranavji]

Windows was capped at Python 3.13 because pythonnet 3.0.x does not support Python 3.14 (requires-python >=3.7,<3.14), which blocked the LibreHardwareMonitor integration. pythonnet 3.1.0 adds Python 3.14 support but drops Python 3.9 (requires-python >=3.10,<3.15), so a plain requirement bump (#1009) would break Python 3.9 users. This PR splits the requirement with environment markers instead — the same pattern already used in requirements.txt for requests, Pillow and numpy — so Python 3.9 through 3.14 all resolve to a compatible pythonnet.

Changes:

• requirements.txt: split pythonnet requirement — ~=3.0.5 for Python 3.9, ~=3.1.0 for Python 3.10+ (supersedes ⬆️ Update pythonnet requirement from ~=3.0.5 to ~=3.1.0 #1009)
• library/pythoncheck.py: remove the Windows-specific 3.13 cap, MAX_PYTHON is now 3.14 on all platforms
• Add Python 3.14 to the Windows system-monitor and simple-program CI matrices (3.9-3.13 rows kept)
• Build Windows packages with Python 3.14, matching the Linux packaging workflow

Tested on Windows 11 with Python 3.14.6:

• pip install -r requirements.txt resolves the full dependency set with no conflicts
• all sources byte-compile cleanly
• LibreHardwareMonitorLib.dll loads via pythonnet 3.1.0 and hardware enumeration works (CPU detected)

🤖 Generated with Claude Code