[mprimeaux]

debt: Addressed proto/v1 evaluation findings; breaking changes to several messages

• feature: Added path field (7) to Uri.
• feature: Added Space message and AngleUnit enum to geometry.proto; every shape carries one Space.
• feature: Added LineSegment and Polyline messages to geometry.proto.
• feature: Added archived_at field (11) to EntityMetadata.
• feature: Added ValidateTags and MaxTagLength Go helpers for EntityMetadata.tags.
• feature: ValidateUUID now requires an RFC 9562-compliant value (Nil, Max, or the RFC 9562 variant with version 1-8). Breaking.
• debt: Renumbered Uri.user_info from 7 to 6. Breaking (wire).
• debt: Changed Uri.port from int32 to uint32; 0 means no port was given. Breaking (API).
• debt: Removed authority field from Uri. Breaking.
• debt: Removed Url message; use Uri. Breaking.
• debt: Changed GeometryType and CoordinateSystem from free-form string messages to enums. Breaking.
• debt: Changed Coordinate to carry only values; Point and Polygon now carry a Space and Coordinates; Polygon is always closed. Breaking.
• debt: Removed Line and Polygon.is_closed from geometry.proto. Breaking.
• debt: Renamed Language.bcp47_tag to bcp47_tags and Geofence.polygon to polygons. Breaking (JSON and API).
• debt: Changed csharp_namespace from SixAfter.Types.V1.WellKnownTypes to SixAfter.Types.V1. Breaking (C# API).
• debt: Removed option cc_enable_arenas from all .proto files.
• debt: Removed the google.api.field_info UUID4 annotation from UUID.value and the googleapis and genproto dependencies.
• debt: Applied buf format to geospatial_location.proto.
• defect: Changed MapPoint.x and MapPoint.y from float to double. Breaking (wire).
• defect: Reshaped TimeZone to name, abbreviation, utc_offset (google.protobuf.Duration), daylight_saving, and central_coordinate; removed utc_offset_std, utc_offset_dst, and TimeZone.TimeOffset. Breaking (wire).
• defect: UUID.MarshalJSON now returns an error for a non-empty value that is not 16 bytes.
• defect: Updated Uri to cite RFC 3986 and UUID to cite RFC 9562.
• defect: Documented negative CompassHeading.true_heading, heading_accuracy, GeospatialLocation.course, and speed as invalid or unknown.
• defect: Documented that unset message fields mean unknown.
• defect: Corrected documentation for EntityMetadata.attributes, tags, and version, TimeZone.central_coordinate, CompassHeading, GeospatialLocation, Version, Country.numeric_code, and EmailAddress.
• defect: Updated UUID helper doc comments to cite RFC 9562 and the Go standard library uuid package.
• defect: Fixed make proto-format to run from the module root and added CHECK=true.
• defect: Fixed make proto-docs to find buf.gen.docs.yaml; generated docs are ignored by git.