feat(desktop): P31 step4 story progress display + evidence shots

- Task panel (T key): a storyline row per occupation, e.g. ju-qing-xian:
shui-wei-yu-shou-cheng, zou-fang-zhong (line name + stage name); absent
for occupation-free saves.
- Occupation select page: minimal hint line showing the selected
  occupation's storyline name.
- Evidence hook LV_STORY_SHOT=1 (+LV_STORY_OCCUPATION, LV_STORY_STAGE):
  boots a real world through the standard bootstrap, advances the story
  via the real dialogue pipeline (chooseDialogueWith bias + Story.onDialogue
  + StoryAnnal append), opens the task panel and saves one back-buffer
  frame, then exits. 4 Xvfb shots (farmer/fisher/peddler/scholar) captured
  under art/ (gitignored, not committed).
- 4 new desktop tests (156 -> 160): panel storyline lines, bias + story
  advance through M5Interaction, no-occupation path stays story-free.

2 files changed, 106 insertions, 0 deletions

diff --git a/src/LivingVillage.Desktop.Tests/LivingVillage.Desktop.Tests.fsproj b/src/LivingVillage.Desktop.Tests/LivingVillage.Desktop.Tests.fsproj
index a0c98b0..d4fa1f5 100644
--- a/src/LivingVillage.Desktop.Tests/LivingVillage.Desktop.Tests.fsproj
+++ b/src/LivingVillage.Desktop.Tests/LivingVillage.Desktop.Tests.fsproj
@@ -10,6 +10,7 @@
     <Compile Include="M6aTests.fs" />
     <Compile Include="M6bTests.fs" />
     <Compile Include="P16UiTests.fs" />
+    <Compile Include="P31StoryUiTests.fs" />
     <Compile Include="PrototypeTests.fs" />
     <Compile Include="MapGenTests.fs" />
     <Compile Include="PerformanceSummaryTests.fs" />
diff --git a/src/LivingVillage.Desktop.Tests/P31StoryUiTests.fs b/src/LivingVillage.Desktop.Tests/P31StoryUiTests.fs
new file mode 100644
index 0000000..562794d
--- /dev/null
+++ b/src/LivingVillage.Desktop.Tests/P31StoryUiTests.fs
@@ -0,0 +1,105 @@
+namespace LivingVillage.Desktop.Tests
+
+open System
+open Microsoft.VisualStudio.TestTools.UnitTesting
+open LivingVillage.Kernel
+open LivingVillage.Kernel.Sim
+open LivingVillage.Desktop
+
+module private P31Harness =
+
+    let atNpc (id: int) (world: World) : World =
+        let npc = world.Npcs.[id]
+        { world with Avatar = { world.Avatar with Pos = npc.Pos } }
+
+    let nearWorld () : World = Sim.initialWorldN 42UL 4 |> atNpc 0
+
+    let npcIndex (NpcId id) : int = id
+
+[<TestClass>]
+type P31StoryUiTests () =
+
+    // ---- 任务面板：剧情线名 + 进度段名 ----
+
+    [<TestMethod>]
+    member _.TaskPanelShowsTheStorylineNameAndStage () =
+        let world = Sim.initialWorldN 42UL 4
+        let state = { Occupation.stateOf Occupation.Fisher with StoryStage = 2 }
+        let view = { M5Interaction.initial with Task = Some state }
+        let _, taskView = M5Interaction.apply ShowTaskPanel world view
+        let lines = M5Interaction.panelLines world taskView
+        Assert.IsTrue(lines |> List.contains "剧情线：水位与收成，走访中", $"lines={lines}")
+
+    [<TestMethod>]
+    member _.TaskPanelShowsConcludedStageAndNoOccupationStaysStoryFree () =
+        let world = Sim.initialWorldN 42UL 4
+        let concluded = { Occupation.stateOf Occupation.Scholar with StoryStage = 3 }
+        let view = { M5Interaction.initial with Task = Some concluded }
+        let _, taskView = M5Interaction.apply ShowTaskPanel world view
+        Assert.IsTrue(
+            M5Interaction.panelLines world taskView
+            |> List.contains "剧情线：庙前的争论，已收束")
+        let _, noneView = M5Interaction.apply ShowTaskPanel world M5Interaction.initial
+        Assert.IsFalse(
+            M5Interaction.panelLines world noneView
+            |> List.exists (fun line -> line.Contains("剧情线")))
+
+    // ---- 对话接线：回应偏差进记忆 + 剧情线推进 + 年鉴写入 ----
+
+    [<TestMethod>]
+    member _.DialogueThroughM5AppliesBiasAndAdvancesTheStory () =
+        let world = { P31Harness.nearWorld () with Tick = 5L * Sim.ticksPerDay }
+        let state = Occupation.stateOf Occupation.Fisher
+        let view = { M5Interaction.initial with Task = Some state; Seed = 42UL }
+        let personality = world.Npcs.[0].Mind.Personality
+        let openedWorld, openedView = M5Interaction.apply Interact world view
+        match openedView.Menu with
+        | None -> Assert.Fail("dialogue menu should open next to a villager")
+        | Some menu ->
+            let finalWorld, finalView = M5Interaction.apply Intent1 openedWorld openedView
+            // 剧情线推进一段（tick 第 5 日 ≥ 开线日）
+            let task = finalView.Task.Value
+            Assert.AreEqual<int>(1, task.StoryStage)
+            // 年鉴写入剧情条目
+            Assert.IsTrue(
+                finalWorld.Annals
+                |> List.exists (fun entry ->
+                    match entry.Kind with
+                    | StoryAnnal -> entry.Summary.Contains("接了件事")
+                    | _ -> false))
+            // 回应偏差可观测：偏差后的回应与纯函数口径一致
+            let biased = Occupation.biasResponse (Some Occupation.Fisher) SmallTalk personality
+            let unbiased = Sim.responseFor SmallTalk personality
+            if biased <> unbiased then
+                Assert.IsTrue(
+                    finalWorld.Annals
+                    |> List.exists (fun entry ->
+                        match entry.Kind with
+                        | DialogueAnnal outcome -> outcome.Response = biased
+                        | _ -> false),
+                    "the biased response must be the one recorded")
+
+    [<TestMethod>]
+    member _.NoOccupationDialogueKeepsTheHistoricResponsePath () =
+        let world = { P31Harness.nearWorld () with Tick = 5L * Sim.ticksPerDay }
+        let view = M5Interaction.initial
+        let openedWorld, openedView = M5Interaction.apply Interact world view
+        match openedView.Menu with
+        | None -> Assert.Fail("dialogue menu should open next to a villager")
+        | Some menu ->
+            let personality = openedWorld.Npcs.[P31Harness.npcIndex menu.Target].Mind.Personality
+            let finalWorld, _ = M5Interaction.apply Intent1 openedWorld openedView
+            let expected = Sim.responseFor SmallTalk personality
+            Assert.IsTrue(
+                finalWorld.Npcs.[0].Mind.Memory
+                |> List.exists (fun memory ->
+                    match memory.Kind with
+                    | Dialogue (_, SmallTalk, response) -> response = expected
+                    | _ -> false))
+            // 无职业不产生剧情条目，剧情线状态不存在
+            Assert.IsFalse(
+                finalWorld.Annals
+                |> List.exists (fun entry ->
+                    match entry.Kind with
+                    | StoryAnnal -> true
+                    | _ -> false))