chore: prepare RoadForge for public alpha

[alteixeira20]

Summary

• remove internal agent, roadmap, audit, planning, and review artifacts
• preserve private workflow material locally outside the public repository
• neutralize AI/tool-specific naming in public product files
• rename personal deployment infrastructure to generic self-hosted deployment
• update public-alpha copy, metadata, contributor guidance, CI, and documentation
• configure frontend commands to target the real workspace package reliably

Validation

• 35 frontend test files passed
• 357 frontend tests passed
• frontend lint passed
• frontend typecheck passed
• Next.js production build passed
• API lint passed
• 211 API tests passed
• Alembic reported no new upgrade operations
• git diff check passed

Notes

Manual browser QA is intentionally deferred until the remaining coding work is complete.

This change does not alter the product access model, roadmap schema, authentication design, or application architecture.