feat: introduce API leveling, post_training to v1alpha

Rather than have a single `LLAMA_STACK_VERSION`, we need to have a `_V1`, `_V1ALPHA`, and `_V1BETA` constant.

This also necessitated addition of `level` to the `WebMethod` so that routing can be handeled properly.

For backwards compat, the `v1` routes are being kept around and marked as `deprecated`. When used, the server will log a deprecation warning.

move:

post_training to v1alpha as it is under heavy development and not near its final state
eval: job scheduling is not implemented. Relies heavily on the datasetio API which is under development missing implementations of specific routes indicating the structure of those routes might change. Additionally eval depends on the inference API which is going to be deprecated, eval will likely need a major API surface change to conform to using completions properly

Signed-off-by: Charlie Doern <cdoern@redhat.com>

llama_stack/schema_utils.py

@@ -13,6 +13,7 @@ from .strong_typing.schema import json_schema_type, register_schema  # noqa: F40
 
 @dataclass
 class WebMethod:
+    level: str | None = None
     route: str | None = None
     public: bool = False
     request_examples: list[Any] | None = None
@@ -23,6 +24,7 @@ class WebMethod:
     descriptive_name: str | None = None
     experimental: bool | None = False
     required_scope: str | None = None
+    deprecated: bool | None = False
 
 
 T = TypeVar("T", bound=Callable[..., Any])
@@ -31,6 +33,7 @@ T = TypeVar("T", bound=Callable[..., Any])
 def webmethod(
     route: str | None = None,
     method: str | None = None,
+    level: str | None = None,
     public: bool | None = False,
     request_examples: list[Any] | None = None,
     response_examples: list[Any] | None = None,
@@ -38,6 +41,7 @@ def webmethod(
     descriptive_name: str | None = None,
     experimental: bool | None = False,
     required_scope: str | None = None,
+    deprecated: bool | None = False,
 ) -> Callable[[T], T]:
     """
     Decorator that supplies additional metadata to an endpoint operation function.
@@ -51,9 +55,10 @@ def webmethod(
     """
 
     def wrap(func: T) -> T:
-        func.__webmethod__ = WebMethod(  # type: ignore
+        webmethod_obj = WebMethod(
             route=route,
             method=method,
+            level=level,
             public=public or False,
             request_examples=request_examples,
             response_examples=response_examples,
@@ -61,7 +66,16 @@ def webmethod(
             descriptive_name=descriptive_name,
             experimental=experimental,
             required_scope=required_scope,
+            deprecated=deprecated,
         )
+
+        # Store all webmethods in a list to support multiple decorators
+        if not hasattr(func, "__webmethods__"):
+            func.__webmethods__ = []  # type: ignore
+        func.__webmethods__.append(webmethod_obj)  # type: ignore
+
+        # Keep the last one as __webmethod__ for backwards compatibility
+        func.__webmethod__ = webmethod_obj  # type: ignore
         return func
 
     return wrap