Add 802.11 HT Operation element

[middleendian]

Dot11 HT Operation

Scope:

• Adds Dot11EltHTOperation for Element ID 61.
• Parses the HT Operation element fixed fields from IEEE Std 802.11n-2009:
  primary channel, secondary channel offset, channel width, RIFS mode, HT
  protection fields, PCO/STBC flags, and the 16-byte Basic MCS Set.
• Adds a focused test/scapy/layers/dot11.uts isolation test with raw
  round-trip coverage.

Spec references used in code comments:

• IEEE Std 802.11n-2009, 7.3.2.57: HT Operation element.
• IEEE Std 802.11n-2009, Figure 7-95o24: HT Operation element format.
• IEEE Std 802.11n-2009, Table 7-43p: HT Operation element field meanings.

Focused test command used:

test/run_tests -t test/scapy/layers/dot11.uts -n 56-62 -F

Result:

PASSED=7 FAILED=0

AI-Assisted: yes (Codex)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.21%. Comparing base (c1367fa) to head (d9b5cb6).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5038      +/-   ##
==========================================
- Coverage   80.22%   80.21%   -0.01%     
==========================================
  Files         387      387              
  Lines       96446    96450       +4     
==========================================
- Hits        77375    77372       -3     
- Misses      19071    19078       +7     

Files with missing lines	Coverage Δ
scapy/layers/dot11.py	91.89% <100.00%> (+0.04%)	⬆️

... and 8 files with indirect coverage changes

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[gpotter2]

Thanks for the PR