Add generationStatus and match3d/runtime fixes

Introduce persistent generationStatus to work summaries (puzzle & match3d) and propagate generation recovery rules across docs and frontend/backends so "generating" is restored from server-side work summary rather than ephemeral front-end notices. Update API server image/asset handling (improve match3d material sheet green/alpha decontamination and promote generatedItemAssets background fields) and add runtime improvements: alpha-based hotspot hit-testing, tray insertion/three-match animation behavior, and session re-read on client-side VectorEngine timeouts/lock-screen interruptions. Many docs, tests and related frontend modules updated/added to reflect these contract and behavior changes.

server-rs/crates/spacetime-client/src/mapper.rs

@@ -3195,6 +3195,7 @@ fn map_match3d_result_draft(
         total_item_count: snapshot.clear_count.saturating_mul(3),
         publish_ready: false,
         blockers: Vec::new(),
+        generated_item_assets_json: snapshot.generated_item_assets_json,
     }
 }
 
@@ -6398,6 +6399,7 @@ pub struct Match3DResultDraftRecord {
     pub total_item_count: u32,
     pub publish_ready: bool,
     pub blockers: Vec<String>,
+    pub generated_item_assets_json: Option<String>,
 }
 
 #[derive(Clone, Debug, PartialEq, Eq)]
@@ -6541,6 +6543,8 @@ struct Match3DDraftJsonRecord {
     tags: Vec<String>,
     clear_count: u32,
     difficulty: u32,
+    #[serde(default)]
+    generated_item_assets_json: Option<String>,
 }
 
 #[derive(Clone, Debug, PartialEq, Eq, serde::Deserialize)]