Implement friendly time formatting in select modules

docs/internal/briefing.md

@@ -36,6 +36,10 @@ Outputs:
 Every registered composition entry has a builder. Unknown or unimplemented
 module IDs fail validation instead of being skipped.
 
+Prompt-facing module values use local, human-readable date and time labels
+where the LLM is expected to reason about report content. Canonical timestamps
+remain in report metadata, source provenance, and integration artifacts.
+
 ## Boundaries
 
 - This package selects and shapes already-collected weather facts for prompts.