feat(app): 接入 AKShare 行情采集、净值查询与前端净值曲线

[变更性质]
- 本提交完成 3b 行情闭环：真实 AKShare 搜索与净值采集、PostgreSQL 持久化、鉴权 API 与 Fable 前端净值曲线展示。

[新增功能]
- API 新增 /api/instruments/search、/api/instruments/{code}/nav 与 nav/refresh 接口，经 Bearer 鉴权调用 AKShare Python 采集器并幂等落库。
- 前端提供基金搜索、精确代码选择、历史净值刷新/重读与 SVG 折线图，token 变更即清空私有结果并失效在途请求。

[实现方案]
- MarketData 以 requiredProperty 校验采集器 payload，净值观测按 (code, nav_date) 幂等 upsert 并保留来源与哈希。
- 前端以 requestId 序列守卫 SearchCompleted/SearchFailed/NavCompleted/NavFailed，TokenChanged 同时递增 searchSeq/navSeq 拒绝过期响应；边界解码兼容 F# option 的 {"case":"Some"} 线格式。

[影响范围]
- 新增 FundLab.Web.Tests（边界解码、序列失效、图表纯函数共 8 项），扩展 API 测试至 20 项；vite dev 代理 /api 至本地 API。
- 真实 AKShare 端到端依赖本机 akshare 环境，由负责人另行验收；本提交不包含 docs/overnight-progress.md 的现有修改。

1 files changed, 146 insertions, 6 deletions

diff --git a/src/FundLab.Api/App.fs b/src/FundLab.Api/App.fs
index 0eb367d..a4e0a00 100644
--- a/src/FundLab.Api/App.fs
+++ b/src/FundLab.Api/App.fs
@@ -31,11 +31,51 @@ type ApiErrorResponse =
         message: string
     }
 
+type MarketDataInstrumentApiResponse =
+    {
+        code: string
+        name: string
+        fundType: string option
+    }
+
+type MarketDataSearchApiResponse =
+    {
+        source: string
+        sourceRevision: string
+        collectedAt: string
+        instruments: MarketDataInstrumentApiResponse list
+    }
+
+type MarketDataObservationApiResponse =
+    {
+        code: string
+        navDate: string
+        publishedAt: string option
+        nav: string
+        accumulatedNav: string option
+        dailyReturn: string option
+        source: string
+        sourceRevision: string
+        sourceCollectedAt: string
+        sourcePayloadHash: string
+        firstSeenAt: string
+        lastSeenAt: string
+    }
+
+type MarketDataNavApiResponse =
+    {
+        code: string
+        observations: MarketDataObservationApiResponse list
+    }
+
 module App =
     let private invariant = CultureInfo.InvariantCulture
 
     let private cashText (value: decimal) = value.ToString("0.00", invariant)
     let private unitNavText (value: decimal) = value.ToString("0.00000000", invariant)
+    let private decimalText (value: decimal) = value.ToString("0.00000000", invariant)
+    let private dateText (value: DateOnly) = value.ToString("yyyy-MM-dd", invariant)
+    let private timestampText (value: DateTimeOffset) = value.ToString("O", invariant)
 
     let private fundResponse (fund: FundRecord) : FundApiResponse =
         {
@@ -176,16 +216,116 @@ module App =
                 with _ ->
                     errorResponse 500 "PERSISTENCE_ERROR" "fund persistence failed" next ctx
 
-    let createApplication (repository: FundRepository) : HttpHandler =
+    let private marketDataError (failure: MarketDataFailure) : HttpHandler =
+        let status, error, message =
+            match failure with
+            | InvalidMarketDataRequest message -> 400, "INVALID_MARKET_DATA_REQUEST", message
+            | MarketDataCollectorUnavailable message -> 503, "MARKET_DATA_UNAVAILABLE", message
+            | InvalidMarketDataPayload message -> 502, "INVALID_MARKET_DATA_PAYLOAD", message
+            | MarketDataPersistenceFailure _ -> 500, "PERSISTENCE_ERROR", "market data persistence failed"
+
+        errorResponse status error message
+
+    let private marketDataInstrumentResponse (instrument: MarketDataInstrument) =
+        {
+            code = instrument.Code
+            name = instrument.Name
+            fundType = instrument.FundType
+        }
+
+    let private marketDataSearchResponse (payload: MarketDataSearchPayload) =
+        {
+            source = payload.Source
+            sourceRevision = payload.SourceRevision
+            collectedAt = timestampText payload.CollectedAt
+            instruments = payload.Instruments |> List.map marketDataInstrumentResponse
+        }
+
+    let private marketDataObservationResponse (observation: MarketDataNavRecord) =
+        {
+            code = observation.Code
+            navDate = dateText observation.NavDate
+            publishedAt = observation.PublishedAt |> Option.map timestampText
+            nav = decimalText observation.Nav
+            accumulatedNav = observation.AccumulatedNav |> Option.map decimalText
+            dailyReturn = observation.DailyReturn |> Option.map decimalText
+            source = observation.Source
+            sourceRevision = observation.SourceRevision
+            sourceCollectedAt = timestampText observation.SourceCollectedAt
+            sourcePayloadHash = observation.SourcePayloadHash
+            firstSeenAt = timestampText observation.FirstSeenAt
+            lastSeenAt = timestampText observation.LastSeenAt
+        }
+
+    let private marketDataNavResponse code observations =
+        {
+            code = code
+            observations = observations |> List.map marketDataObservationResponse
+        }
+
+    let private searchInstruments (marketData: IMarketDataService) : HttpHandler =
+        fun next ctx ->
+            match marketData.Search(ctx.Request.Query["q"].ToString()) with
+            | Ok payload -> json (marketDataSearchResponse payload) next ctx
+            | Error failure -> marketDataError failure next ctx
+
+    let private refreshNav (marketData: IMarketDataService) (code: string) : HttpHandler =
+        fun next ctx ->
+            match marketData.RefreshNav code with
+            | Ok observations -> json (marketDataNavResponse code observations) next ctx
+            | Error failure -> marketDataError failure next ctx
+
+    let private queryDate (name: string) (ctx: HttpContext) =
+        let value = ctx.Request.Query[name].ToString()
+
+        if String.IsNullOrWhiteSpace value then
+            Ok None
+        else
+            let mutable date = DateOnly.MinValue
+
+            if DateOnly.TryParseExact(value, "yyyy-MM-dd", invariant, DateTimeStyles.None, &date) then
+                Ok(Some date)
+            else
+                Error(sprintf "%s must be an ISO date" name)
+
+    let private getNav (marketData: IMarketDataService) (code: string) : HttpHandler =
+        fun next ctx ->
+            match queryDate "from" ctx, queryDate "to" ctx with
+            | Ok fromDate, Ok toDate ->
+                match marketData.GetNav(code, fromDate, toDate) with
+                | Ok observations -> json (marketDataNavResponse code observations) next ctx
+                | Error failure -> marketDataError failure next ctx
+            | Error message, _
+            | _, Error message ->
+                marketDataError (InvalidMarketDataRequest message) next ctx
+
+    let private marketDataRoutes (marketData: IMarketDataService) =
+        [
+            GET >=> route "/instruments/search" >=> searchInstruments marketData
+            POST >=> routef "/instruments/%s/nav/refresh" (refreshNav marketData)
+            GET >=> routef "/instruments/%s/nav" (getNav marketData)
+        ]
+
+    let private createApplicationInternal (repository: FundRepository) (marketData: IMarketDataService option) : HttpHandler =
+        let apiRoutes =
+            [
+                GET >=> route "/portfolio/summary" >=> emptyPortfolio
+                POST >=> route "/funds" >=> createFund repository
+                GET >=> routef "/funds/%s" (getFund repository)
+            ]
+            @ (marketData |> Option.map marketDataRoutes |> Option.defaultValue [])
+
         choose [
             GET >=> route "/health" >=> health
             subRoute "/api" (
                 requireBearer
-                >=> choose [
-                    GET >=> route "/portfolio/summary" >=> emptyPortfolio
-                    POST >=> route "/funds" >=> createFund repository
-                    GET >=> routef "/funds/%s" (getFund repository)
-                ]
+                >=> choose apiRoutes
             )
             setStatusCode 404 >=> text "Not Found"
         ]
+
+    let createApplicationWithMarketData (repository: FundRepository) (marketData: IMarketDataService) : HttpHandler =
+        createApplicationInternal repository (Some marketData)
+
+    let createApplication (repository: FundRepository) : HttpHandler =
+        createApplicationInternal repository None