P13-T5: Validate prompt reduction and multi-client stability

[SoundBlaster]

Description

Implements P13-T5 validation for persistent broker behavior.

Key changes:

• Added tests/integration/test_broker_multi_client.py covering:
  • sequential short-lived client reuse of one broker-owned upstream process
  • concurrent multi-client routing stability under load
  • single upstream launch count across many short-lived sessions
• Added process-churn comparison artifact (direct baseline vs broker mode)
• Added manual prompt-validation artifact and recorded current status
• Archived P13-T5 task artifacts and updated workflow bookkeeping (SPECS/Workplan.md, SPECS/INPROGRESS/next.md, SPECS/ARCHIVE/INDEX.md)

Validation report: SPECS/ARCHIVE/P13-T5_Validate_prompt_reduction_and_multi_client_stability/P13-T5_Validation_Report.md

Type of Change

• Bug fix
• New feature
• Documentation update
• Refactoring
• CI/CD improvement

Quality Gates

Before submitting, ensure all quality gates pass:

make check

Or run individually:

• make test - All tests pass with ≥90% coverage (equivalent commands run: pytest, pytest --cov; 577 passed, 5 skipped, 92.31% coverage)
• make lint - No linting errors (ruff check src/ tests/)
• make format - Code is properly formatted
• make typecheck - Type checking passes (mypy src/)
• make doccheck - Documentation is synced with DocC (if docs changed)

Documentation Sync

If you modified files in docs/, ensure corresponding DocC files are also updated:

docs/ file	DocC file
docs/installation.md	mcpbridge-wrapper.docc/Installation.md
docs/cursor-setup.md	mcpbridge-wrapper.docc/CursorSetup.md
docs/claude-setup.md	mcpbridge-wrapper.docc/ClaudeCodeSetup.md
docs/codex-setup.md	mcpbridge-wrapper.docc/CodexCLISetup.md
docs/troubleshooting.md	mcpbridge-wrapper.docc/Troubleshooting.md
docs/architecture.md	mcpbridge-wrapper.docc/Architecture.md
docs/environment-variables.md	mcpbridge-wrapper.docc/EnvironmentVariables.md
README.md	mcpbridge-wrapper.docc/mcpbridge-wrapper.md

• Documentation changes are synced with DocC catalog (or N/A)

Testing

• Added/updated tests for new functionality
• All tests pass locally
• Manually tested the changes

Checklist

• Code follows the project's style guidelines
• Self-review completed
• Comments added for complex code
• Documentation updated (if needed)
• No new warnings generated
• PR title is descriptive