test(coverage): expand coverage for stream and lifecycle modules

[mikehostetler]

Summary

• add focused unit coverage for Jido.Shell.Exec (run/4, run_in_dir/5, and path escaping)
• add streaming and fallback coverage for Jido.Shell.StreamJson, including:
  • session-server streaming path
  • JSON/raw line parsing (including trailing-buffer parsing)
  • timeout/cancel/crash/error handling
  • heartbeat callbacks
  • fallback eligibility behavior and callback safety
• add provisioning and teardown coverage for Jido.Shell.SpriteLifecycle, including:
  • successful provisioning and teardown flows
  • retry/warning flows
  • missing API and missing client/sprite-name branches
• ratchet CI coverage gate from 73.0 to 83.5 in .github/workflows/ci.yml

Validation

• mix test test/jido/shell/exec_test.exs test/jido/shell/stream_json_test.exs test/jido/shell/sprite_lifecycle_test.exs --seed 0
• mix test --seed 0
• mix quality
• mix coveralls
• mix coveralls.json && MIX_ENV=test mix run -e 'minimum = 83.5; data = Jason.decode!(File.read!("cover/excoveralls.json")); coverages = data["source_files"] |> Enum.flat_map(& &1["coverage"]); relevant = Enum.count(coverages, &(!is_nil(&1))); missed = Enum.count(coverages, &(&1 == 0)); percent = (relevant - missed) * 100.0 / relevant; rounded = Float.round(percent, 2); IO.puts("Coverage gate: #{rounded}% (minimum #{minimum}%)"); if percent < minimum, do: System.halt(1)'

Coverage

• total coverage improved from ~73.3% baseline to ~83.9-84.1% locally
• module-level improvements:
  • lib/jido_shell/stream_json.ex: 0.0% -> 90.6%
  • lib/jido_shell/sprite_lifecycle.ex: 0.0% -> 80.2%
  • lib/jido_shell/exec.ex: 0.0% -> 88.8%