Schema.toTaggedUnion('type') already provides LLMEvent.guards but uses
kebab-case bracket access (LLMEvent.guards['tool-call']). Adds an LLMEvent.is
namespace with camelCase aliases that delegate to the same guards, so
consumers can write events.filter(LLMEvent.is.toolCall) instead of
events.filter(LLMEvent.guards['tool-call']).
Migrated all callsites in src/llm.ts and the two test files for consistency.
LLMEvent.guards / .match / .cases / .isAnyOf remain available for callers
who want the Effect-canonical API.
Kit Langton
f4de3e801e