fix(approval): clamp approvals.timeout at the config-read chokepoint (#83220)

Widen the salvaged gate-site clamp to the bug class. The gate min() from
the contributor PR capped the gate bound at 360s, which would break the
#79719 contract (gate must extend while a legitimate >360s approval
prompt is answerable) and left the sibling overflow sites live: the CLI
prompt thread.join, the gateway poll deadline, and human_wait_ceiling
all consume the same config value.

Clamp once in _get_approval_timeout() via agent.deadline.MAX_SAFE_TIMEOUT_S
(1 year - semantically unbounded, platform-safe). The gate keeps its
approvals.timeout-tracking behavior above 360s; 7 regression tests pin
lock-acquire/thread-join safety and the gate-extension contract.

Bilateral E2E: with approvals.timeout=1e20 in a real config.yaml, main
crashes every consumer with OverflowError; this branch survives all 5
probes.

agent/tool_executor.py

@@ -154,12 +154,13 @@ def _authorization_gate_lock_timeout() -> float:
     try:
         from tools.approval import human_wait_ceiling
 
-        # Clamp to _AUTHORIZATION_GATE_LOCK_TIMEOUT_S: the gate serializes
-        # parallel dispatch — it should never wait longer than a wedged-holder
-        # timeout even when approvals.timeout is set very large (or infinite).
-        # On macOS, unbounded values overflow threading.Lock.acquire's timespec
-        # and raise OverflowError (#83220).
-        return min(human_wait_ceiling(), _AUTHORIZATION_GATE_LOCK_TIMEOUT_S)
+        # human_wait_ceiling is platform-safety-capped (agent/deadline.py
+        # MAX_SAFE_TIMEOUT_S): a huge approvals.timeout can no longer overflow
+        # Lock.acquire's time_t on macOS (#83220). Deliberately NOT min()'d
+        # with _AUTHORIZATION_GATE_LOCK_TIMEOUT_S — the gate must never give
+        # up while a legitimate approval prompt is still answerable (#79719),
+        # so a configured approvals.timeout above 360s must extend the gate.
+        return human_wait_ceiling()
     except Exception:
         return _AUTHORIZATION_GATE_LOCK_TIMEOUT_S