feat: support arbitrary slices and arrays in ToSlice

[AdamMagued]

Summary

Fixes #355

Currently, ToSliceE only converts slices that match []any or []map[string]any in its type switch. When provided typed slices (such as []int, []string, or slices of structs) or fixed-size arrays, ToSliceE fails with an error unable to cast to []any.

Technical Root Cause

ToSliceE lacked reflection fallback to decompose arbitrary slice and array types into generic []any elements.

Changes

• In ToSliceE, check for nil explicitly, then use reflection to handle reflect.Slice and reflect.Array kinds in the default switch branch.
• Allocate []any with length matching rv.Len() and copy elements using rv.Index(idx).Interface().
• Add test coverage in TestSlice covering []int, []string, arrays ([3]int, [2]string), and slices of structs.

Verification

• Ran go test -v .: all tests passed cleanly.
• Ran go vet .: no violations.

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