build(metadata): lower minimum Python to 3.11

zarr-metadata is a typing-only foundational package consumed by
libraries; supporting one Python version below the current minimum
widens the audience at minimal cost.

The only blocker was PEP 695 generic class syntax in `common.py`:

    class NamedConfig[TName: str, TConfig: ...](TypedDict):

Rewritten to the PEP 484 `Generic[T]` form, which works on 3.11+.
The two affected classes carry `# noqa: UP046` comments since the
ruff rule pushes toward the newer syntax that we deliberately avoid.

All other modern features (PEP 604 `X | Y` unions at runtime,
`NotRequired`, `extra_items=` via typing_extensions, `ReadOnly`)
already work on 3.11.

Verified: package imports and all 6 tests pass on Python 3.11.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: d-v-b

packages/zarr-metadata/pyproject.toml

@@ -7,7 +7,7 @@ name = "zarr-metadata"
 version = "0.1.0"
 description = "Spec-defined metadata types for Zarr v2 and v3."
 readme = "README.md"
-requires-python = ">=3.12"
+requires-python = ">=3.11"
 license = "MIT"
 authors = [
     { name = "Davis Bennett", email = "davis.v.bennett@gmail.com" },
@@ -18,6 +18,7 @@ classifiers = [
     "License :: OSI Approved :: MIT License",
     "Programming Language :: Python",
     "Programming Language :: Python :: 3",
+    "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
     "Programming Language :: Python :: 3.13",
     "Programming Language :: Python :: 3.14",
@@ -47,4 +48,4 @@ checks = [
 include = ["src"]
 enableExperimentalFeatures = true
 typeCheckingMode = "strict"
-pythonVersion = "3.12"
+pythonVersion = "3.11"

packages/zarr-metadata/src/zarr_metadata/common.py

@@ -7,30 +7,40 @@
 """
 
 from collections.abc import Mapping, Sequence
-from typing import NotRequired, TypedDict
+from typing import Generic, NotRequired, TypedDict, TypeVar
 
 from typing_extensions import ReadOnly
 
 JSON = str | int | float | bool | Mapping[str, "JSON"] | Sequence["JSON"] | None
 """Any valid JSON value."""
 
 
-class NamedConfig[TName: str, TConfig: Mapping[str, object]](TypedDict):
+TName = TypeVar("TName", bound=str)
+TConfig = TypeVar("TConfig", bound=Mapping[str, object])
+
+
+class NamedConfig(TypedDict, Generic[TName, TConfig]):  # noqa: UP046
     """
     Named-config envelope with optional configuration.
 
     Generic with two parameters: name literal and configuration mapping.
+
+    Uses the PEP 484 ``Generic[T]`` form rather than PEP 695 ``[T]`` syntax
+    so the package supports Python 3.11.
     """
 
     name: ReadOnly[TName]
     configuration: NotRequired[ReadOnly[TConfig]]
 
 
-class NamedRequiredConfig[TName: str, TConfig: Mapping[str, object]](TypedDict):
+class NamedRequiredConfig(TypedDict, Generic[TName, TConfig]):  # noqa: UP046
     """
     Named-config envelope with required configuration.
 
     Generic with two parameters: name literal and configuration mapping.
+
+    Uses the PEP 484 ``Generic[T]`` form rather than PEP 695 ``[T]`` syntax
+    so the package supports Python 3.11.
     """
 
     name: ReadOnly[TName]