docs: correct how a wait-mode call actually dies on a dead source

Branch review caught the docs claiming something the code does not do.
CHANGELOG, README and the design's behaviour matrix all said a
force-opened source under circuit_open=wait waits out the full stall
window. It does not: the probe let through after each cooldown is a
real attempt, so it burns a max_attempts slot like any other, and a
401 source usually runs out of retry budget first -- reason is
retry_exhausted, not stalled. Which budget wins depends on
max_attempts against the cooldowns and the stall window.

The behaviour is right; only the prose was wrong. Charging the probe
to the retry budget is exactly the split issue #8 settled: the
question is who spends max_attempts, and a probe does send a real
request. A test now pins it so the claim cannot drift again.

Also drops the planned "woke up" log line. Each wait round already
logs on entry with its duration, and a still-blocked wake-up logs the
next round immediately, so a second line would only double the volume.

README.md

@@ -413,7 +413,7 @@ SQLite 侧**不建议**对着一个大库文件跑 `DELETE` + `VACUUM`,而应**
 
 熔断的设计前提是"这个源坏了,把流量导到别的源"。**只配了一个源时这个前提不成立**,同一段代码做的事变成"这个源坏了,所以整个 scope 停止服务":开路期间每一次调用都在几毫秒内失败,`MAX_ATTEMPTS` 一格用不上,一个网络包都没发出去。中转抖动几十秒就足以打断一条跑了几小时的长任务。
 
-`wait` 档改变的**只是**"调用方当场失败还是排队等":等待期间照样一个请求都不发,熔断对配额和钱包的保护完整保留。代价是单次调用的最坏墙钟被拉长到 `{SCOPE}__BACKPRESSURE__STALL_WINDOW_S`(缺省 300 秒)——包括密钥失效(401/403)这种一击即熔的情形,库无法区分"密钥坏了"和"中转抖了",选 `wait` 就是声明"宁可等也不要当场死"。多源部署保持 `fail_fast`:有源可换时,换源比等待快。
+`wait` 档改变的**只是**"调用方当场失败还是排队等":等待期间照样一个请求都不发,熔断对配额和钱包的保护完整保留。代价是单次调用的最坏墙钟被拉长,上限为 `{SCOPE}__BACKPRESSURE__STALL_WINDOW_S`(缺省 300 秒)。**`wait` 不豁免重试预算**——冷却结束后放行的探针是一次真实尝试,失败照样烧一格 `MAX_ATTEMPTS`;因此密钥失效(401/403)这类一击即熔的源通常更早以 `reason=retry_exhausted` 失败,而非等满窗口的 `stalled`。库无法区分"密钥坏了"和"中转抖了",选 `wait` 就是声明"宁可等也不要当场死"。多源部署保持 `fail_fast`:有源可换时,换源比等待快。
 
 该键与 `{SCOPE}__QUOTA_FULL` 同形但**不可互相替代**:配额满是"排队等自己的份额"(必然轮到),熔断开路是"等这个源恢复"(未必恢复),所以两者分开配置。