Constrain maybe::assign to types with has_value()/value()

[HFTrader]

Summary

Four bugs found via clang-tidy 23 (trunk) analysis:

1. Constrain maybe::assign template (commit 1)

• Add requires clause to all three assign template overloads
• The unconstrained template accepted any type including plain int, causing compilation errors
• Fixes Error while building with clang-21 #5, Build failure with Clang 23 (trunk): maybe::assign calls .has_value() on non-maybe types #6

2. Fix is_common_comparison_category concept (commit 2)

• Changed && to || — the concept was always false since no type can simultaneously be strong_ordering, weak_ordering, AND partial_ordering
• This made lexicographical_compare_three_way uncallable

3. Fix maybe_value_storage::assign self-assignment (commit 2)

• hard_reset() destroyed m_storage before the assignment read from the maybe parameter
• If maybe aliased m_storage, this was use-after-destroy
• Added __builtin_addressof guard

4. Fix divide_by calling wrong functions (commit 2)

• Wrap/saturate branches called wrap_mul/sat_mul instead of wrap_div/sat_div
• Author-acknowledged with "TODO: This looks wrong"

Build verification

• Clean 594/594 build with Clang 23.0.0git (llvm-project main, d7eec97bd83f)
• PCH disabled (-DCAT_PCH=OFF)

Fixes #5, #6