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/mappers.rs

@@ -134,12 +134,11 @@ pub(super) fn map_match3d_draft_response(
     draft: Match3DResultDraftRecord,
 ) -> Match3DResultDraftResponse {
     // 中文注释：session draft 自身也可能携带生成素材快照，不能只依赖 work detail 回读补齐 UI 背景和容器图。
-    let generated_item_assets = parse_match3d_generated_item_assets(
-        draft.generated_item_assets_json.as_deref(),
-    )
-    .into_iter()
-    .map(Match3DGeneratedItemAsset::from)
-    .collect::<Vec<_>>();
+    let generated_item_assets =
+        parse_match3d_generated_item_assets(draft.generated_item_assets_json.as_deref())
+            .into_iter()
+            .map(Match3DGeneratedItemAsset::from)
+            .collect::<Vec<_>>();
     let background_asset = find_match3d_generated_background_asset(&generated_item_assets);
     let mut response = Match3DResultDraftResponse {
         profile_id: draft.profile_id,