Propagate the current entity to entity_blueprint's CurrentEntityContext

Problem/Motivation

ai_plus resolves the entity for the page the user is on and propagates it to the agent as prompt tokens (current_entity_context / current_view_mode). AI tools and skills, however, execute outside the prompt and cannot read those tokens, so they had no way to know which entity or bundle the user is viewing.

entity_blueprint provides a shared CurrentEntityContext service precisely for passing this context out-of-band to tool execution, but ai_plus was not populating it, so guidance that depends on the current page (for example bundle-specific tool guidance) could not resolve.

Proposed resolution

• In TokenPropagationSubscriber, after capturing the current entity for the prompt tokens, also call CurrentEntityContext::set() with the entity type and bundle, so tools and skills can resolve guidance for the current page.

API changes

• TokenPropagationSubscriber gains a CurrentEntityContext (entity_blueprint) constructor dependency, injected via autowiring. No other signature changes.