fix(deployments): surface partial failure decision (#664)

[Rish-it]

Summary

• deliver the partial-failure decision on the first terminal SSE event, before the stream closes
• persist and replay the decision across reconnects and finished-deployment hydration
• clear cached decision state after keep/reject while keeping warning-only deploys from opening the modal

Verification

• full API Vitest suite passed
• full dashboard Vitest suite passed: 96 files, 1,084 tests
• API and dashboard TypeScript checks passed
• focused decision lifecycle regressions passed: 25 tests

Closes #664

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