Extract settings-based KI registration out of KnowledgeBase

[DaviddeBest-TNO]

Problem

KnowledgeBase has two KI registration paths: the direct API (ask_ki, answer_ki, post_ki, react_ki, ki_from_info) and the settings path (ki_from_settings, ki_from_settings_with_default_handler). The settings path keeps a private _build_settings reference and guards every call with if not self._build_settings: raise ValueError(...).

This mixes two concerns: the KB's runtime identity/behaviour, and its build-time configuration source. KnowledgeBase as a concept shouldn't know about KnowledgeBaseSettings.

Proposed solution

Extract settings-based KI registration into a thin KnowledgeBaseBuilder (or a KnowledgeBase subclass) that holds the settings reference and exposes ki_from_settings. KnowledgeBase.from_settings() returns this builder/subclass. The base KnowledgeBase has no _build_settings field and no settings-guarded methods.

Benefits

• KnowledgeBase is testable without any settings knowledge.
• The settings-path code concentrates in the builder (locality).
• Callers who don't use settings never see those methods in autocomplete.