Clarify OpenAI client timeout precedence

docs/consumers/pkg-scriptorium.md

@@ -20,12 +20,17 @@ fields:
 | `PromptDir` | Prompt-definition directory, required unless a prompt source option is supplied. |
 | `ProfileDir` | Optional custom profile directory over built-ins. |
 | `SchemaDir` | Schema directory; empty uses `.`. |
-| `Timeout` | Default timeout for the built-in OpenAI-compatible client. |
-| `HTTPClient` | Optional HTTP client for that built-in client. |
+| `Timeout` | Base timeout for the built-in OpenAI-compatible client when `HTTPClient` is absent or has a zero timeout. A non-positive value uses the internal default. |
+| `HTTPClient` | Optional HTTP client for that built-in client. It is cloned; a non-zero `Timeout` on it takes precedence over `Config.Timeout` as the base timeout. |
 
 Nil options are ignored. Invalid construction, including
 `WithLLMClient(nil)`, returns an error matching `ErrInvalidConfig`.
 
+An effective positive `timeout_seconds` replaces the base timeout. An explicit
+request override of zero disables the HTTP-client timeout. The timeout is
+otherwise inherited from the supplied client, `Config.Timeout`, or the internal
+default in that order.
+
 Source options replace their matching directory source:
 
 - prompts: `WithPromptFS(fsys, root)`, `WithPromptFile(path)`;