feat(occupation): P11 存档 v3 today-task 尾段（annals 后追加）+ 双向兼容

Occupation.State 增 Today: DailyTask option（State 声明移至 DailyTask 之后；TaskToken 保留为 v3 前缀占位扩展位）。WorldSave：saveWith 有任务时在 annals 之后追加尾段 task-today|<template>|<state>|<offered>|<due>|npc-none/some|tile-none/some；无任务/无职业不追加（默认 None = 旧行为，v2 逐字节不变）。load 重构为内部 parse 返回 (World, Occupation.State option)：尾段可选——旧 v3（P10 版式无尾段）新 reader 读出 Today=None；v1/v2 无任务；尾段后多余 token 或未知模板 token 拒绝（不吞档）。loadFromFileWith 顺手修正：不再经 stateOf 重置，前缀 task/stage 与 Today 全量保真。5 例测试：尾段位置（marker 在 annal 之后）+ 全字段 round-trip + 重存逐字节一致、无任务 v3 旧版式、v1/v2 无尾段 + 未知模板拒绝、尾段后垃圾拒绝、字节级双跑一致。

1 files changed, 11 insertions, 9 deletions

diff --git a/src/LivingVillage.Kernel/Occupation.fs b/src/LivingVillage.Kernel/Occupation.fs
index e0507ae..a3c37bd 100644
--- a/src/LivingVillage.Kernel/Occupation.fs
+++ b/src/LivingVillage.Kernel/Occupation.fs
@@ -43,15 +43,6 @@ module Occupation =
         | Peddler -> { Kind = Peddler; InitialMoney = 90; InitialEnergy = 100.0f; InitialInventory = [ Sim.Food, 6; Sim.Spice, 4 ] }
         | Scholar -> { Kind = Scholar; InitialMoney = 70; InitialEnergy = 100.0f; InitialInventory = [ Sim.Food, 10; Sim.Scroll, 2 ] }
 
-    /// Placeholder carried in save v3 until the task-system slice lands (design §3).
-    type State =
-        { Profile: Profile
-          TaskToken: int
-          StoryStage: int }
-
-    let stateOf (kind: Kind) : State =
-        { Profile = profileOf kind; TaskToken = 0; StoryStage = 0 }
-
     // ---- 每日任务（design §3）：Kernel 侧纯函数片，不进 Sim.step 数值路径 ----
 
     type TaskState =
@@ -169,3 +160,14 @@ module Occupation =
                   OfferedTick = offered
                   DueTick = offered + Sim.ticksPerDay - 1L
                   State = Offered }
+
+    /// 挂在玩家侧的职业状态，随存档 v3 保存（design §2）。
+    /// Today = 当日任务（§3）；TaskToken 保留为 v3 前缀占位扩展位（恒 0，暂未启用）。
+    type State =
+        { Profile: Profile
+          TaskToken: int
+          Today: DailyTask option
+          StoryStage: int }
+
+    let stateOf (kind: Kind) : State =
+        { Profile = profileOf kind; TaskToken = 0; Today = None; StoryStage = 0 }