Implement consolidated summary and failed example reporting in orchestrator

[vovka]

Background

Currently, the orchestrator prints only a dummy summary at the end of parallel test runs. For full usability, it must print a consolidated summary, including failed examples, and test statistics across all processes.

Requirements

1. Formatter Data Collection

   • Each formatter (test process) must collect:
     • List of failed examples with:
       • Description
       • File/line location
       • Error message (backtrace optional)
     • Example counters:
       • Total examples
       • Failed examples.
       • Pending examples
     • Elapsed time for its process (optional but useful for reporting)
     • If there is already exist rspec built-in mechanism for this, use it, do not invent new.

2. Summary Transmission

   • At the end of the test suite (on dump_summary or close), each formatter must send a new IPC message to the orchestrator.
   • Define a new IPC message type (e.g., summary).
   • Payload should include all items listed above.
   • Pending example details should NOT be sent—only the count.

3. Orchestrator Summary Rendering

   • The orchestrator must collect all summary messages from all processes.
   • Once all are received, it should:
     • Merge all failures into a single list.
     • Sum total, failed, and pending example counts across all processes.
     • Sum or list all process run times (if available).
   • Print a consolidated summary at the end, including:
     • List of failed examples, with details. (Should look like standard rspec failures output - test name, error, expected/got, diff (3 previous items colorized), backtrace.)
     • Statistics: N examples, M failures, K pending.
     • Total wall clock time.
     • Sum of process times.
   • Pending examples: only print the total count (no details).

4. Robustness

   • The orchestrator should robustly handle missing or delayed summaries (e.g., with a timeout or best-effort fallback), to avoid hanging indefinitely.
   • Prefer IPC for summary transmission unless unworkable; do not use files except as a fallback.

5. Simplicity

   • Prefer the simplest working solution. Do not introduce unnecessary abstractions.

Acceptance Criteria

• After all test processes finish, the orchestrator prints a consolidated summary and failure listing, as described above.
• No pending test details are printed (only the count).
• Solution uses IPC for summary sharing.
• If a process crashes or fails to report, orchestrator prints the summary with what it received, and logs a warning.

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This issue is based on design analysis and requirements clarification. If anything is unclear or you see edge cases not covered, please add questions or comments before implementation.