Enforce Genarrative play-type SOP and update docs

Rewrite Genarrative play-type integration guidance across .codex and .hermes to define a platform-level SOP: default to form/image workbench, unify single-image asset slots (CreativeImageInputPanel), standardize series-material sheet->cut->transparent->OSS pipeline, and forbid copying legacy chat/agent workflows as the default. Add decision-log entry freezing the SOP and a pitfalls note warning against direct reuse of old play tools. Update CONTEXT.md and docs/README.md, add a new PRD file, and apply related small server-side changes (module-auth, spacetime-client mappers and runtime) to align back-end code with the new contracts and flows.

server-rs/crates/api-server/src/match3d/vector_engine_gemini.rs

@@ -26,6 +26,7 @@ pub(super) async fn generate_match3d_material_sheet(
 
     Ok(Match3DMaterialSheet {
         task_id: generated.task_id,
+        prompt,
         image,
     })
 }