[http-client-python] Map numeric scalar to Python float (#10563)

The Python emitter mapped the TypeSpec `numeric` scalar to `int`,
truncating floating-point values for operations like:

```typespec
op nooooooo(): numeric;
```

Since `numeric` is the parent of both integer and float scalars, `int`
is unsound — `float` is the correct Python representation.

### Changes

- **`packages/http-client-python/emitter/src/types.ts`**: In
`sdkScalarKindToPythonKind`, change `numeric: "integer"` → `numeric:
"float"`.
- **Changeset**: Added a `fix` entry for `@typespec/http-client-python`.

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: msyyc <70930885+msyyc@users.noreply.github.com>
Co-authored-by: Yuchao Yan <yuchaoyan@microsoft.com>

Author: Copilot

.chronus/changes/fix-python-numeric-float-2026-4-29-23-55-0.md

@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@typespec/http-client-python"
+---
+
+Fix TypeSpec `numeric` scalar type being emitted as `int` in Python; it is now emitted as `float`.

packages/http-client-python/emitter/src/types.ts

@@ -436,7 +436,7 @@ function emitConstant(context: PythonSdkContext, type: SdkConstantType) {
 }
 
 const sdkScalarKindToPythonKind: Record<string, string> = {
-  numeric: "integer",
+  numeric: "float",
   integer: "integer",
   safeint: "integer",
   int8: "integer",