feat: Phase 3 Prompt 10 enterprise POC and production readiness

[RPK2103]

Summary

Completes SignalForge Phase 3 Prompt 10: Microsoft-aligned enterprise POC and
startup pitch readiness.

Product

• authenticated executive briefing experience
• reusable navigation
• NovaBank executive demo flow
• evidence / estimate / recommendation honesty

Enterprise POC

• POC lifecycle and success framework
• security/governance questionnaire
• data onboarding plan
• Microsoft-aligned architecture options
• ROI hypothesis model
• buyer and positioning package

Engineering

• production-readiness and deployment review
• dependency lockfile remediation
• reproducible frontend install/build
• release and rollback guidance
• documentation contracts
• expanded frontend and E2E validation

Safety

• no new migration
• no public demo mutation endpoint
• no authentication bypass
• no Microsoft endorsement claim
• no fabricated customer/ROI/traction claims
• no employee ranking

Validation

Final local validation results are documented in the implementation report and
will be revalidated by required GitHub Actions before merge.

Prompt 10 must not merge until all mandatory remote checks are green.