feat: Add explicit runway visual range unit to parsed METAR runway data

[Copilot]

This ports the upstream runway-visibility unit change into the Python parser so runway visual range no longer loses unit semantics. FT runway ranges are now represented explicitly instead of being implied from raw token format.

• Model update: explicit runway unit

  • Added LengthUnit enum (METERS, FEET) in metar_taf_parser.model.enum.
  • Extended RunwayInfo with a new unit field and included it in object representation.

• Parser update: deterministic unit assignment

  • Updated runway parsing paths (Rxx/#### and Rxx/####V####) to set:
    • LengthUnit.FEET when token includes FT
    • LengthUnit.METERS otherwise
  • Centralized unit decoding in a small helper to keep both parse branches consistent.

• Coverage update: runway unit expectations

  • Extended command- and parser-level tests to assert unit values for both meter-based and FT runway visual range inputs.

# before: unit was implicit/absent
# after: unit is explicit on RunwayInfo
runway.unit = LengthUnit.FEET if token_suffix == "FT" else LengthUnit.METERS

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

🎉 This PR is included in version 1.11.0 🎉

The release is available on:

• v1.11.0
• GitHub release

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