docs(tools): widen the 182 reachability shape and finish the note's two language-binding facts

"Reachable only through a raw register() whose parameters is
array-rooted" was too narrow. A root oneOf reaches the same 182: the
union arm propagates listDepth unchanged because `A | B` opens no
bracket, so an array branch starts its chain at 0 exactly as an array
root does. Say "root opens an array chain -- rooted at the array, or at
an array branch of a root oneOf", in the JSDoc and the test comment,
and assert the union shape alongside the array-rooted one.

The note's Decision paragraph said the flavor guard is reached under
"a language that has a renderer but no flavor entry, and a test covers
it". The test uses ruby, absent from both tables, and the mechanism is
that schemas() reaches run_code's getters without passing
requireCodeRuntime -- so any language absent from the flavor table hits
it. State that instead.

The Consequences paragraph recorded the language-binding obligation as
two reads, assembly and execution. Within one projection there are more:
run_code's description and parameters getters each call
resolveFlavor(peekRuntime()) and schemaOf destructures both, so a reload
between them yields one schema whose halves name different languages.

packages/core/tools/src/py-types.ts

@@ -191,9 +191,11 @@ const MAX_CLASS_NAME_BASE = 120
  * - Argument annotation, `async def f(self, args: chain) -> Y:` — the `(` IS
  *   still open around it: 180 `list[` plus `Literal[` plus the paren, 182, the
  *   worst case. Reachable only through a raw `register()` whose `parameters`
- *   is array-rooted; `defineTool` compiles an object root, so the annotation
- *   is a bare TypedDict class name or `dict[str, Any]` — neither carries a
- *   chain.
+ *   root opens an array chain — rooted at the array, or at an array branch of
+ *   a root `oneOf`, which inherits the enclosing depth because a union adds no
+ *   brackets. `defineTool` compiles an object root, so the annotation is a
+ *   bare TypedDict class name or a one-bracket `dict[str, Any]` when that
+ *   object degrades — never a chain.
  *
  * A CPython grammar limit, not a deployment choice, so it is fixed rather than
  * configurable. The sibling `ts-types` renderer needs no counterpart: nothing