Split focused CLI command runner modules

[Widthdom]

Summary

• Extracted query batch-mode handling from QueryCommandRunner into QueryCommandRunner.Batch.
• Extracted ProgramRunner dispatch/helper command handling into ProgramRunner.Dispatch.
• Added unreleased internal changelog fragments for both issues.

Validation

• dotnet build CodeIndex.sln -c Debug -p:UseSharedCompilation=false
• dotnet test tests/CodeIndex.Tests/CodeIndex.Tests.csproj -c Debug --filter "FullyQualifiedName~QueryCommandRunnerTests.RunBatch" -p:UseSharedCompilation=false
• dotnet test tests/CodeIndex.Tests/CodeIndex.Tests.csproj -c Debug --filter "FullyQualifiedName~ProgramRunnerTests" -p:UseSharedCompilation=false
• dotnet test CodeIndex.sln -c Release -p:UseSharedCompilation=false
• dotnet run --project tools/CodeIndex.Changelog -- check
• cdidx index . --files src/CodeIndex/Cli/QueryCommandRunner.cs src/CodeIndex/Cli/QueryCommandRunner.Batch.cs changelog.d/unreleased/3380.internal.md --json
• cdidx index . --files src/CodeIndex/Cli/ProgramRunner.cs src/CodeIndex/Cli/ProgramRunner.Dispatch.cs changelog.d/unreleased/3418.internal.md --json
• cdidx index . --commits 9f96e71d7 --json
• cdidx index . --commits a677391bb --json
• Codex adversarial review: no blocking/actionable issues found.

Changelog

• changelog.d/unreleased/3380.internal.md
• changelog.d/unreleased/3418.internal.md

Fixes #3380
Fixes #3418