fix(config): validate codex settings and allow claude concurrency override

adapters/claude/config/settings.json

@@ -12,7 +12,7 @@
     ]
   },
   "env": {
-    "CLAUDE_CODE_MAX_TOOL_USE_CONCURRENCY": "5"
+    "CLAUDE_CODE_MAX_TOOL_USE_CONCURRENCY": "__CLAUDE_CODE_MAX_TOOL_USE_CONCURRENCY__"
   },
   "statusLine": {
     "type": "command",

adapters/codex/config/config.toml

@@ -8,7 +8,6 @@ status_line = ["model", "reasoning", "approval-mode", "project-name", "git-branc
 [agents]
 enabled = true
 max_concurrent_threads_per_session = 5
-max_depth = 1
 
 [features]
 hooks = true