feat: Remove unsigned integer types from core types

Remove uint8, uint16, uint32, and uint64 from CORE_TYPES dictionary.
These unsigned integer types are MySQL-specific and not portable to
PostgreSQL and other database backends.

Unsigned types can still be used as native types (with existing
warning system for non-core types), but are no longer recommended
as part of DataJoint's portable core type system.

This establishes a clean foundation for multi-database support in v2.1.

Part of v2.0 core type system revision.

Author: dimitri-yatsenko

src/datajoint/declare.py

@@ -25,13 +25,9 @@
     "float32": (r"float32$", "float"),
     "float64": (r"float64$", "double"),
     "int64": (r"int64$", "bigint"),
-    "uint64": (r"uint64$", "bigint unsigned"),
     "int32": (r"int32$", "int"),
-    "uint32": (r"uint32$", "int unsigned"),
     "int16": (r"int16$", "smallint"),
-    "uint16": (r"uint16$", "smallint unsigned"),
     "int8": (r"int8$", "tinyint"),
-    "uint8": (r"uint8$", "tinyint unsigned"),
     "bool": (r"bool$", "tinyint"),
     # UUID (stored as binary)
     "uuid": (r"uuid$", "binary(16)"),