docs(mathx): add godoc comment to Numerical type constraint

[amshithnair]

Problem

The Numerical type constraint in core/mathx/range.go is the only exported type in the go-zero core/ packages without a godoc comment. Every other exported type, function, and variable follows the Go convention of having a documentation comment.

Solution

Added a standard godoc comment:

// Numerical is a constraint that permits any numeric type.
type Numerical interface {
    ~int | ~int8 | ~int16 | ~int32 | ~int64 |
        ~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 |
        ~float32 | ~float64
}

Impact

• Documentation-only change — no behavior modified
• No public API changes
• No breaking changes
• Improves go doc output and IDE hover documentation

Testing performed

go vet ./core/mathx/...   # PASS

Files changed

• core/mathx/range.go — added 1 comment line

[kevwan]

LGTM — adds a clear, accurate godoc comment to the exported Numerical constraint. The description "permits any numeric type" is correct given the full union of ~int, ~int8 … ~float32, ~float64, and ~complex64, ~complex128 variants.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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