Add Coordinate (geo)

[vhrcgcom]

Description

Implement Coordinate as a ValueObject in the geo module.

Spec: composite: Latitude + Longitude

Implementation checklist

• Create src/geo/coordinate.rs
• Implement ValueObject trait
• Add #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
• Export from src/geo/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

Coordinate is a composite value object. Depends on Latitude and Longitude.

	Type
Input	CoordinateInput { latitude: Latitude, longitude: Longitude }
Output	String — e.g. "50.0755, 14.4378"

Validation

Both fields are already validated Latitude and Longitude instances — no additional validation required.

Extra methods

• latitude() -> &Latitude
• longitude() -> &Longitude

References

• ROADMAP.md
• CONTRIBUTING.md