feat: Shadow Run Design Phase — 252+ trading-day validation framework

Implements foundation for model evaluation per AGENTS.md v16.0:
- Domain models: ShadowRunCommand, ShadowRunResult, ValidationGates
- Data backfiller: OHLCV + fee schedule collection from KRX API
- Replay engine: Historical model simulation with signal/order/fill tracking
- Metrics calculator: Sharpe, Calmar, PBO, DSR, Max Drawdown, Win Rate
- Hangfire job orchestrator: Async shadow run execution (q-research queue)
- Integration tests: 4/4 passing (backfill, replay, metrics, validation)

Contract validation:
- Input: Model ID, date window, market phase filter
- Output: Immutable result with phase breakdown, gate status
- Gates: PBO ≤ 20%, DSR ≥ 95%, cost 2x positive

Architecture adherence:
- SOLID: Single responsibility (backfiller, replay, calculator separation)
- Complexity: Cyclomatic < 10 per method
- Safety: Idempotent replay via deterministic price/order fills
- Necessity: Grounded in CLAUDE.md § "Validation Gates"
- Pattern: Vertical Slice (Command → Handler → Queries)

Not included (future):
- Full 252-day rehearsal (requires market data backfill)
- Downstream inbox consumers (event delivery mechanisms)
- Phase segmentation logic (Bull/Bear/Sideways attribution)

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/KArtSell.Modules.ModelOperations/KArtSell.Modules.ModelOperations.csproj

@@ -1,4 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <NoWarn>$(NoWarn);CA1716;CA1822;CA1848;CA1860;CA1873</NoWarn>
+  </PropertyGroup>
   <ItemGroup>
     <ProjectReference Include="../KArtSell.BuildingBlocks/KArtSell.BuildingBlocks.csproj" />
     <PackageReference Include="FastEndpoints" />