Automated coverage is below the 80 percent threshold #29

The test suite passes, but measured coverage is below the requested 80 percent threshold. Running dotnet test ARCP.slnx --collect:"XPlat Code Coverage" --results-directory TestResults produced 60 passing tests, and a union over the Cobertura reports measured 1780 covered lines out of 2512 valid lines, which is 70.86 percent line coverage. The same union measured 553 covered branches out of 991 valid branches, which is 55.80 percent branch coverage. The lowest covered production files include Arcp.Core/Transport/StdioTransport.cs at 0 of 52 lines, Arcp.Runtime/Credentials/CredentialRedaction.cs at 4 of 15 lines, Arcp.Runtime/SessionState.Dispatch.cs at 31 of 98 lines, and Arcp.Runtime/JobContext.cs at 19 of 59 lines.

The relevant locations are tests/Arcp.UnitTests/, tests/Arcp.IntegrationTests/, tests/Arcp.ConformanceTests/, tests/Arcp.AspNetCore.Tests/, and the generated coverage reports under TestResults/*/coverage.cobertura.xml.

Fix prompt: Add targeted tests that raise line coverage above 80 percent and branch coverage materially closer to that threshold. Prioritize currently uncovered transport behavior for StdioTransport, malformed dispatch and error branches in SessionState.Dispatch, budget and credential redaction paths, and cancellation or terminal paths in JobContext and JobManager. Add a documented coverage command or CI coverage gate using Coverlet so future changes can reproduce the line and branch numbers consistently.