💥 feat(planning)!: 拆分 C# ICSP 并默认 Rust

* 新增可选 Flyshot.CSharp.Planning 项目

* 将 icsp 映射到 Rust 后端并拒绝旧 icsp_rust

* 补充后端注册、文档、调试页和回归测试

BREAKING CHANGE: method=icsp 现在默认调用 Rust 后端；C# ICSP 改为 method=icsp-csharp，旧 method=icsp_rust 不再作为正式入口。

tests/Flyshot.Core.Tests/RustIcspPlannerParityTests.cs

@@ -1,4 +1,5 @@
 using Flyshot.Core.Domain;
+using Flyshot.CSharp.Planning;
 using Flyshot.Core.Planning;
 using Flyshot.Native.Planning;
 
@@ -19,8 +20,8 @@ public sealed class RustIcspPlannerParityTests
         PlannedTrajectory managed = new ICspPlanner().Plan(request);
         PlannedTrajectory native = new RustIcspPlanner().Plan(request);
 
-        Assert.Equal(PlanningMethod.Icsp, managed.Method);
-        Assert.Equal(PlanningMethod.IcspRust, native.Method);
+        Assert.Equal(PlanningMethod.IcspCSharp, managed.Method);
+        Assert.Equal(PlanningMethod.Icsp, native.Method);
         AssertTrajectoryMatches(managed, native, tolerance: 1e-9);
     }
 
@@ -35,8 +36,8 @@ public sealed class RustIcspPlannerParityTests
         PlannedTrajectory managed = new ICspPlanner(enforceFinalScale: false).Plan(request);
         PlannedTrajectory native = new RustIcspPlanner(options).Plan(request);
 
-        Assert.Equal(PlanningMethod.Icsp, managed.Method);
-        Assert.Equal(PlanningMethod.IcspRust, native.Method);
+        Assert.Equal(PlanningMethod.IcspCSharp, managed.Method);
+        Assert.Equal(PlanningMethod.Icsp, native.Method);
         AssertTrajectoryMatches(managed, native, tolerance: 1e-9);
     }
 
@@ -116,7 +117,7 @@ public sealed class RustIcspPlannerParityTests
                 .Select(_ => new IoAddressGroup([]))
                 .ToArray());
 
-        return new TrajectoryRequest(robot, program, PlanningMethod.Icsp);
+        return new TrajectoryRequest(robot, program, PlanningMethod.IcspCSharp);
     }
 
     /// <summary>