Add BoundedString (primitives) #67

Description

Implement BoundedString as a ValueObject in the primitives module.

Spec: BoundedString<const MIN: usize, const MAX: usize> via const generics

Implementation checklist

• Create src/primitives/boundedstring.rs
• Implement ValueObject trait
• Add #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
• Export from src/primitives/mod.rs and prelude
• Unit tests: valid input · empty input · invalid format · normalisation
• Doc comment with # Example block
• Update status in ROADMAP.md from ⬜ to ✅

Implementation detail

Input / Output

BoundedString uses const generics to encode the allowed length range at the type level.

Type declaration

pub struct BoundedString<const MIN: usize, const MAX: usize>(String);

Normalization

Trim surrounding whitespace.

Validation

• Length in Unicode characters (not bytes) after trimming must be >= MIN and <= MAX.
• MIN must be <= MAX; enforce with a compile-time assertion or a runtime check that returns a Custom error variant.

Extra methods

None beyond the trait.

Notes

The ValueObject impl will have type Input = String and type Output = String. Use chars().count() for length, not .len(), to count Unicode characters correctly.

References

• ROADMAP.md
• CONTRIBUTING.md