Add D&D extraction fallback profile

docs/internal/dnd.md

@@ -22,10 +22,11 @@ does not repeat their JSON shapes or schemas.
 ## Family Composition
 
 The D&D registrar registers the family’s artifact codecs, extractors, typed
-append-order mergers, normalizers, validators, prompt assets, and default
-validator chains. Each extractor and normalizer has a stable module spec,
-strict option decoding, and a typed builder. Configuration remains the
-canonical owner of the exact keys and validator order.
+append-order mergers, normalizers, validators, prompt assets, fallback LLM
+profile asset, and default validator chains. Each extractor and normalizer has
+a stable module spec, strict option decoding, and a typed builder.
+Configuration remains the canonical owner of the exact keys and validator
+order.
 
 Private structured-LLM response schemas are deliberately minimal. They reject
 invalid JSON structure, missing required fields, incompatible types, and
@@ -41,6 +42,13 @@ reference, and transcript assets instead of copying their text into individual
 modules. A manifest’s declared sequence, including cache-control placement, is
 part of the prompt behavior.
 
+Every maintained D&D LLM prompt selects `dnd-extraction` as its default
+profile. The D&D registrar embeds that fallback profile with the maintained
+OpenRouter model, timeout, and service-tier policy. An operator may provide a
+complete profile with the same ID through the configured PromptKit source; that
+definition replaces the fallback rather than merging with it. The fallback
+leaves reasoning and optional sampling controls unspecified.
+
 All extraction prompts share this four-message rendered prefix: the system
 message without cache control, the identity message without cache control, the
 campaign-reference message with ephemeral cache control, and the chunk