Add a new narrative forecast module and remove the unimplemented daily forecast stub

docs/config.md

@@ -129,8 +129,8 @@ name the variable only; they should not contain the token value.
 - `default`: missing-source behavior for optional sources. One of `error`, `warn`, or `none`. Default: `warn`.
 - `sources`: optional map of source-specific overrides, using the same policy values.
 
-Hourly forecast data is required for generated reports. Optional sources and
-stub source slots use the missing-source policy.
+Hourly forecast data is required for generated reports. Optional sources use
+the missing-source policy.
 
 ### `scriptorium`
 
@@ -196,6 +196,7 @@ reports:
     deterministic_modules:
       - metadata
       - current_conditions
+      - narrative_forecast
       - id: area_forecast_discussion
         options:
           sections:
@@ -209,8 +210,8 @@ combinations, duplicate stanza names, and invalid options fail config loading.
 includes all available AFD sections.
 
 The module registry accepts all module IDs documented in
-[Module Contract Internals](internal/module.md). Modules without builders are
-valid in composition but do not emit YAML stanzas.
+[Module Contract Internals](internal/module.md). Unknown or unimplemented
+module IDs fail validation instead of being skipped.
 
 ## Secrets