Hold a C# namespace's fields and functions in a static class [patch]

[matt-edmondson]

Fixes #155

What was wrong

CSharpGenerator.GenerateNamespace wrote every member straight into the namespace, so the issue's repro came out as:

namespace Geometry
{
    public static readonly int Origins = 2;

    public int twice(int n) { ... }
}

C# has no member outside a type, so this fails with CS0116. The same members directly in a SourceFile fail with CS0106.

Change

• A namespace's FieldDeclaration, FunctionDeclaration and VariableDeclaration members are gathered into a public static class, placed where the first of them was declared:

  namespace Geometry
  {
      public static class Geometry
      {
          public static readonly int Origins = 2;
  
          public static int twice(int n) { ... }
      }
  
      public class Point { }
  }

• Name: the namespace's last segment, or Globals at file scope. If a type, enum or alias beside it already has that name, the class gets a Globals suffix to avoid CS0101.
• static: each held member is written static (CS0708). A held const variable is left as plain const, because static const is CS0504. Locals inside a held function are untouched: the generator tracks the member being held by reference, not with a flag, so nothing in its body is affected.
• Types, enums, aliases and nested namespaces stay where they are.
• The file-scope member loop moves out of LanguageGeneratorBase.GenerateSourceFile into an overridable GenerateFileMembers, so C# can do the same at file scope. Other generators behave the same as before.

Tests

• CSharpScopeMemberTests (6 tests): the namespace holder and its ordering, locals staying locals, const without static, the name-collision fallback, file-scope members, and no holder when a namespace holds only types.
• New CSharpGeneratedSourceCompilesTests, matching the C/C++/Rust/Go ones. It writes the generated file next to a driver that uses every declaration from outside, runs dotnet build, and is inconclusive when no dotnet is on the path.
• With the generator change reverted, 5 of the 7 new tests fail, including the compile test with the issue's CS0106. The two that still pass are guards. With the change, all pass.
• Full Coder.Test suite: 1207 passed, 0 failed. dotnet format --verify-no-changes is clean on the touched files.

Not covered

The compile test builds the issue's shapes, not all of CompiledExemplar. Compiling the whole exemplar as C# still hits #127 (abstract readonly on Shape, fixed separately in #225) and other gaps tracked in #162. ExemplarReflectionTableTests uses C++ type names such as holo::reflect::FieldInfo, so it can't be compiled as C# however its members are placed.

This PR and #225 both edit CSharpGenerator's function-modifier code, so whichever merges second will need a small merge.

🤖 Generated with Claude Code

https://claude.ai/code/session_018FP1DMG4WYMABYwTfyb2Xd

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Generated by Claude Code

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Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
96.3% Coverage on New Code
0.0% Duplication on New Code

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