fix(agent): align LLM wall timeout with sustained goals for main + subagents

Centralize runner_wall_llm_timeout_s in session goal_state metadata helpers so
spawned subagents inherit the same policy as AgentLoop without coupling to
long_task. Pass optional resolver into SubagentManager and add tests.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/session/test_goal_state.py

@@ -8,8 +8,10 @@ from nanobot.session.goal_state import (
     goal_state_runtime_lines,
     goal_state_ws_blob,
     parse_goal_state,
+    runner_wall_llm_timeout_s,
     sustained_goal_active,
 )
+from nanobot.session.manager import SessionManager
 
 
 def test_runtime_lines_empty_when_no_metadata():
@@ -105,3 +107,25 @@ def test_sustained_goal_active_true_when_active():
 def test_sustained_goal_active_respects_legacy_thread_goal_key():
     meta = {"thread_goal": {"status": "active", "objective": "Legacy."}}
     assert sustained_goal_active(meta) is True
+
+
+def test_runner_wall_llm_timeout_uses_metadata_override(tmp_path):
+    sm = SessionManager(tmp_path)
+    assert (
+        runner_wall_llm_timeout_s(
+            sm,
+            "cli:test",
+            metadata={GOAL_STATE_KEY: {"status": "active", "objective": "x"}},
+        )
+        == 0.0
+    )
+    assert runner_wall_llm_timeout_s(sm, "cli:test", metadata={}) is None
+
+
+def test_runner_wall_llm_timeout_reads_session_when_metadata_missing(tmp_path):
+    sm = SessionManager(tmp_path)
+    sess = sm.get_or_create("c:d")
+    sess.metadata = {GOAL_STATE_KEY: {"status": "active", "objective": "z"}}
+    assert runner_wall_llm_timeout_s(sm, "c:d") == 0.0
+    sess.metadata = {}
+    assert runner_wall_llm_timeout_s(sm, "c:d") is None