修复资产计费边界风险

资产生成预扣费改为 fail-closed，避免钱包异常时继续调用外部生成

新增钱包退款 outbox，退款失败时本地落盘并后台重放

拼图首图后台任务改用 SpacetimeDB claim 表实现跨实例互斥

计费 ledger id 统一绑定 request_id，并让前端重试复用 x-request-id

同步 SpacetimeDB bindings、后端架构文档和 Hermes 决策记录

server-rs/crates/module-puzzle/src/application.rs

@@ -20,6 +20,14 @@ pub struct PuzzleAgentSessionProcedureResult {
     pub error_message: Option<String>,
 }
 
+#[cfg_attr(feature = "spacetime-types", derive(SpacetimeType))]
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PuzzleBackgroundCompileTaskProcedureResult {
+    pub ok: bool,
+    pub claimed: bool,
+    pub error_message: Option<String>,
+}
+
 #[cfg_attr(feature = "spacetime-types", derive(SpacetimeType))]
 #[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
 pub struct PuzzleWorksProcedureResult {

server-rs/crates/module-puzzle/src/commands.rs

@@ -68,6 +68,25 @@ pub struct PuzzleDraftCompileInput {
     pub compiled_at_micros: i64,
 }
 
+#[cfg_attr(feature = "spacetime-types", derive(SpacetimeType))]
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PuzzleBackgroundCompileTaskClaimInput {
+    pub task_id: String,
+    pub claim_id: String,
+    pub session_id: String,
+    pub owner_user_id: String,
+    pub claimed_at_micros: i64,
+}
+
+#[cfg_attr(feature = "spacetime-types", derive(SpacetimeType))]
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PuzzleBackgroundCompileTaskReleaseInput {
+    pub task_id: String,
+    pub claim_id: String,
+    pub session_id: String,
+    pub owner_user_id: String,
+}
+
 #[cfg_attr(feature = "spacetime-types", derive(SpacetimeType))]
 #[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
 pub struct PuzzleDraftCompileFailureInput {