feat(wal): implement recovery orchestrator with tail truncation

- wal/recover.go: top-level Recover() function that orchestrates scan + replay + truncation
  Reads MANIFEST/CURRENT for recovery segment ID, handles tail corruption by truncating
- Comprehensive tests for empty dir, full flow, tail corruption, and MANIFEST updates
- All tests 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": "2026-06-12T05:57:16.412Z",
+      "updated_at": "2026-06-12T06:02:11.867Z",
       "session_ids": [
         "opencode:ses_145c3bae9ffeTB2zbsTym0Cev8"
       ],
@@ -107,6 +107,19 @@
           "status": "completed",
           "ended_at": "2026-06-12T05:57:16.412Z",
           "elapsed_ms": 23149
+        },
+        "todo:17": {
+          "task_key": "todo:17",
+          "task_label": "17",
+          "task_title": "WAL recovery: tail truncation + main flow",
+          "session_id": "opencode:ses_14597418effebiQE4kDHOCEW0E",
+          "agent": "Sisyphus-Junior",
+          "category": "unspecified-high",
+          "updated_at": "2026-06-12T06:02:11.867Z",
+          "started_at": "2026-06-12T06:01:55.154Z",
+          "status": "completed",
+          "ended_at": "2026-06-12T06:02:11.867Z",
+          "elapsed_ms": 16713
         }
       }
     }
@@ -114,7 +127,7 @@
   "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": "2026-06-12T05:57:16.412Z",
+  "updated_at": "2026-06-12T06:02:11.867Z",
   "session_ids": [
     "opencode:ses_145c3bae9ffeTB2zbsTym0Cev8"
   ],
@@ -213,6 +226,19 @@
       "status": "completed",
       "ended_at": "2026-06-12T05:57:16.412Z",
       "elapsed_ms": 23149
+    },
+    "todo:17": {
+      "task_key": "todo:17",
+      "task_label": "17",
+      "task_title": "WAL recovery: tail truncation + main flow",
+      "session_id": "opencode:ses_14597418effebiQE4kDHOCEW0E",
+      "agent": "Sisyphus-Junior",
+      "category": "unspecified-high",
+      "updated_at": "2026-06-12T06:02:11.867Z",
+      "started_at": "2026-06-12T06:01:55.154Z",
+      "status": "completed",
+      "ended_at": "2026-06-12T06:02:11.867Z",
+      "elapsed_ms": 16713
     }
   },
   "agent": "atlas"

.omo/plans/phase1-wal.md

@@ -1287,7 +1287,7 @@ Max Concurrent: 6 (Wave 1b)
 
   **Commit**: YES (with Tasks 15, 17)
 
-- [ ] 17. WAL recovery: tail truncation + main flow
+- [x] 17. WAL recovery: tail truncation + main flow
 
   **What to do**:
   - 创建 `wal/truncation.go`：尾部截断持久化