feat(lib): migrate to SQLite WAL backend for robust concurrency (FW-L1)

- Replaces python fcntl.flock with SQLite BEGIN IMMEDIATE.
- Status/Reconcile read from SQLite SSOT, with YAML fallback.
- Explicitly documented tradeoff: YAML is no longer a real-time view.
- Handles PRAGMA wal_checkpoint(TRUNCATE) safely outside transactions.

skills/tmux-agent-orchestrate-status/scripts/status.sh

@@ -37,8 +37,20 @@ home = os.environ['HOME_DIR']
 claude_project_dir = os.environ.get('CLAUDE_PROJECT_DIR', f"{home}/.claude/projects")
 drift = json.loads(os.environ['DRIFT_JSON'])
 
-with open(yaml_path) as f:
-    d = yaml.safe_load(f) or {}
+db_path = yaml_path.replace('.yaml', '.db')
+d = {}
+import sqlite3
+try:
+    if os.path.exists(db_path):
+        conn = sqlite3.connect(db_path, timeout=10.0)
+        row = conn.execute('SELECT data FROM state WHERE id=1').fetchone()
+        if row: d = json.loads(row[0])
+        conn.close()
+    elif os.path.exists(yaml_path):
+        with open(yaml_path) as f:
+            d = yaml.safe_load(f) or {}
+except Exception:
+    pass
 
 alive = set(drift.get('tmux_sessions_alive', []))
 drift_by_name = {}