feat(orchestrator): add Discuss Phase and PRD creation workflow

[mubaidr]

Pull Request Checklist

• I have read and followed the CONTRIBUTING.md guidelines.
• I have read and followed the Guidance for submissions involving paid services.
• My contribution adds a new instruction, prompt, agent, skill, or workflow file in the correct directory.
• The file follows the required naming convention.
• The content is clearly structured and follows the example format.
• I have tested my instructions, prompt, agent, skill, or workflow with GitHub Copilot.
• I have run npm start and verified that README.md is up to date.

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Description

• Introduce Discuss Phase for medium/complex objectives, generating context‑aware options and logging architectural decisions
• Add PRD creation step after discussion, storing the PRD in docs/prd.yaml
• Refactor Phase 1 to pass task clarifications to researchers
• Update Phase 2 planning to include multi‑plan selection for complex tasks and verification with gem‑reviewer
• Enhance Phase 3 execution loop with wave integration checks and conflict filtering

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Type of Contribution

• New instruction file.
• New prompt file.
• New agent file.
• New plugin.
• New skill file.
• New agentic workflow.
• Update to existing instruction, prompt, agent, plugin, skill, or workflow.
• Other (please specify):

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Additional Notes

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By submitting this pull request, I confirm that my contribution abides by the Code of Conduct and will be licensed under the MIT License.