Add SPC convective outlook briefing module

docs/internal/briefing.md

@@ -28,7 +28,8 @@ Outputs:
   supported reports, fact requirements, missing-data behavior, and builder
 - `module.Output` values for source-oriented stanzas:
   `metadata`, `current_conditions`, `narrative_forecast`, `hourly_forecast`,
-  `alert_digest`, `area_forecast_discussion`, and `weather_story`
+  `alert_digest`, `spc_convective_outlooks`,
+  `area_forecast_discussion`, and `weather_story`
 - `module.Output` values for derived stanzas:
   `derived_daily_summary`, `derived_daypart_summaries`, `precip_timing`,
   `outdoor_windows`, and `tomorrow_planning`
@@ -86,6 +87,9 @@ return an error for invalid required inputs.
   forecast discussion, and weather story stanzas.
 - Alert digest output distinguishes checked empty alert data from missing alert
   source data.
+- SPC convective outlook output distinguishes checked empty outlook data from
+  missing outlook source data and omits GeoJSON geometry from prompt-facing
+  fields.
 
 ## Tests