Fix: Replace os.sched_getaffinity() with os.cpu_count() for Windows/macOS compatibility

[ishansurdi]

Problem

os.sched_getaffinity() is a Linux-only function and causes AttributeError on Windows and macOS systems, preventing the script from running on these platforms.

Solution

Replace os.sched_getaffinity(0) with os.cpu_count() which is cross-platform and available on all operating systems.

Changes

• Updated jackhmmer_n_cpu default value
• Updated hmmsearch_n_cpu default value
• Updated hhsearch_n_cpu default value

Testing

• ✅ Tested on Windows - works correctly
• ✅ Detects CPU count properly
• ✅ Maintains same logic (min of cpu_count and 8)
• ✅ Includes fallback to 8 if cpu_count() returns None

Compatibility

• Works on: Linux, Windows, macOS
• Python: 3.8+
• No breaking changes

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