feat(wal): implement WAL writer with group commit and recovery batch replay

- wal/commit_queue.go: bounded buffered channel for write requests
- wal/writer.go: single-goroutine main loop implementing 11-step write flow
  with group commit, sequence allocation, MemTable publish/abort, write-stopped
- wal/recovery.go: BatchReplayer interface, ReplayBatch, ReplaySegmentFile,
  RecoverFromSegments with fragment reassembly and tail corruption handling
- Comprehensive tests for all modules, all pass with -race

.omo/boulder.json

@@ -8,7 +8,7 @@
       "plan_name": "phase1-wal",
       "status": "active",
       "started_at": "2026-06-12T05:09:32.588Z",
-      "updated_at": "2026-06-12T05:49:50.501Z",
+      "updated_at": "2026-06-12T05:57:16.412Z",
       "session_ids": [
         "opencode:ses_145c3bae9ffeTB2zbsTym0Cev8"
       ],
@@ -94,6 +94,19 @@
           "status": "completed",
           "ended_at": "2026-06-12T05:49:50.501Z",
           "elapsed_ms": 106010
+        },
+        "todo:13": {
+          "task_key": "todo:13",
+          "task_label": "13",
+          "task_title": "Commit queue + WAL writer main loop",
+          "session_id": "opencode:ses_1459dbbd5ffewqrKSfu5f6t38q",
+          "agent": "Sisyphus-Junior",
+          "category": "deep",
+          "updated_at": "2026-06-12T05:57:16.412Z",
+          "started_at": "2026-06-12T05:56:53.263Z",
+          "status": "completed",
+          "ended_at": "2026-06-12T05:57:16.412Z",
+          "elapsed_ms": 23149
         }
       }
     }
@@ -101,7 +114,7 @@
   "active_plan": "/home/dailz/workspace/src/go-kv/.omo/plans/phase1-wal.md",
   "started_at": "2026-06-12T05:09:32.588Z",
   "status": "active",
-  "updated_at": "2026-06-12T05:49:50.501Z",
+  "updated_at": "2026-06-12T05:57:16.412Z",
   "session_ids": [
     "opencode:ses_145c3bae9ffeTB2zbsTym0Cev8"
   ],
@@ -187,6 +200,19 @@
       "status": "completed",
       "ended_at": "2026-06-12T05:49:50.501Z",
       "elapsed_ms": 106010
+    },
+    "todo:13": {
+      "task_key": "todo:13",
+      "task_label": "13",
+      "task_title": "Commit queue + WAL writer main loop",
+      "session_id": "opencode:ses_1459dbbd5ffewqrKSfu5f6t38q",
+      "agent": "Sisyphus-Junior",
+      "category": "deep",
+      "updated_at": "2026-06-12T05:57:16.412Z",
+      "started_at": "2026-06-12T05:56:53.263Z",
+      "status": "completed",
+      "ended_at": "2026-06-12T05:57:16.412Z",
+      "elapsed_ms": 23149
     }
   },
   "agent": "atlas"

.omo/plans/phase1-wal.md

@@ -1009,7 +1009,7 @@ Max Concurrent: 6 (Wave 1b)
 
   **Commit**: YES (with Task 13)
 
-- [ ] 13. Commit queue + WAL writer main loop
+- [x] 13. Commit queue + WAL writer main loop
 
   **What to do**:
   - 创建 `wal/commit_queue.go`：`CommitQueue` — 写请求队列
@@ -1233,7 +1233,7 @@ Max Concurrent: 6 (Wave 1b)
 
   **Commit**: YES (with Tasks 16, 17)
 
-- [ ] 16. WAL recovery: fragment collector + batch replay
+- [x] 16. WAL recovery: fragment collector + batch replay
 
   **What to do**:
   - 创建 `wal/recovery.go`：恢复核心逻辑