Centralize shared D&D LLM assets

assets/dnd/shared/prompts/common-dnd-extraction-evidence.md

@@ -0,0 +1,14 @@
+Transcript units are the only evidence for extracted events and factual claims.
+Campaign and registry references may disambiguate names, aliases, speakers, or
+other identities, but they do not establish events, participation, effects, or
+source evidence.
+
+Every reported factual claim must be supported by cited transcript units. Use
+integer `start_unit_id` and `end_unit_id` values from the transcript. Omit
+`source_id`; Notarius assigns the current source identity.
+
+When supporting evidence is non-contiguous, use multiple narrow ranges rather
+than a broad range that bridges unrelated conversation.
+
+Return exactly one JSON object and no explanatory text. Output only the
+configured JSON object and fields defined by its response schema.