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/api-server/src/match3d/handlers.rs

@@ -751,7 +751,6 @@ pub async fn generate_match3d_background_image_for_work(
     )?;
     let prompt = normalize_match3d_background_prompt(payload.prompt.as_str());
     ensure_non_empty(&request_context, MATCH3D_WORKS_PROVIDER, &prompt, "prompt")?;
-    let prompt_fingerprint = build_match3d_prompt_fingerprint(prompt.as_str());
 
     let context =
         load_match3d_work_asset_context(&state, &request_context, &authenticated, &profile_id)
@@ -763,7 +762,12 @@ pub async fn generate_match3d_background_image_for_work(
         config,
         assets,
     } = context;
-    let billing_asset_id = format!("{}:{}:{}", session_id, profile_id, prompt_fingerprint);
+    let billing_asset_id = format!(
+        "{}:{}:{}",
+        session_id,
+        profile_id,
+        request_context.request_id()
+    );
     let (generated_background, generated_assets) = execute_billable_asset_operation_with_cost(
         &state,
         owner_user_id.as_str(),
@@ -860,7 +864,6 @@ pub async fn generate_match3d_container_image_for_work(
     )?;
     let prompt = normalize_match3d_background_prompt(payload.prompt.as_str());
     ensure_non_empty(&request_context, MATCH3D_WORKS_PROVIDER, &prompt, "prompt")?;
-    let prompt_fingerprint = build_match3d_prompt_fingerprint(prompt.as_str());
 
     let context =
         load_match3d_work_asset_context(&state, &request_context, &authenticated, &profile_id)
@@ -874,7 +877,9 @@ pub async fn generate_match3d_container_image_for_work(
     } = context;
     let billing_asset_id = format!(
         "{}:{}:{}:container",
-        session_id, profile_id, prompt_fingerprint
+        session_id,
+        profile_id,
+        request_context.request_id()
     );
     let (generated_background, generated_assets) = execute_billable_asset_operation_with_cost(
         &state,
@@ -1017,7 +1022,7 @@ pub async fn generate_match3d_item_assets_for_work(
         session_id,
         profile_id,
         billed_item_count,
-        build_match3d_prompt_fingerprint(generation_plan.billing_fingerprint_source().as_str())
+        request_context.request_id()
     );
     let generated_assets = execute_billable_asset_operation_with_cost(
         &state,