Add NPC registry grounding for spell extraction

internal/modules/dnd/extract/spells/assets/prompts/dnd.spells.yaml

@@ -17,6 +17,9 @@ inputs:
   - name: glossary
     required: false
     content_type: text/plain
+  - name: npcs
+    required: false
+    content_type: application/json
 messages:
   - role: system
     content_file: ./sharedassets/common-dnd-system.md
@@ -30,6 +33,8 @@ messages:
       type: ephemeral
   - role: user
     content_file: ./catalog.md
+  - role: user
+    content_file: ./npc_registry.md
   - role: user
     content_file: ./task.md
   - role: user

internal/modules/dnd/extract/spells/assets/prompts/npc_registry.md

@@ -0,0 +1,11 @@
+The optional canonical NPC registry for this extraction is provided below as
+durable JSON. Use it only to prefer exact canonical NPC names and recognize
+their aliases when the transcript identifies a caster.
+
+Registry entries are grounding material, not evidence that a spell was cast.
+Do not extract a spell, caster, effect, or source reference from the registry.
+NPC source references describe registry provenance and may belong to another
+session; they are never spell evidence. Preserve the existing player and party
+policy for identifying PCs from the transcript.
+
+{{ input "npcs" }}