Add PR prompt: replace 180s hard timeout with real progress + stall d…

[Kyle-Wang0211]

…etection

Comprehensive implementation prompt covering:

• Server-side: parse nerfstudio stdout for real progress (SfM 40%, training 55%, export 5%)
• Client-side: replace Timeout.withTimeout(180) with stall-based detection (5min no-progress)
• Absolute safety cap at 2 hours for worst-case scenarios
• iOS background task handling with beginBackgroundTask
• Cross-platform guardrails (Linux compilation, #if canImport guards)
• Constants SSOT registration, drift registry, acceptance criteria updates
• Full test requirements and migration checklist

https://claude.ai/code/session_01QbMRnehvC5Z7A3QzHcYGEJ

What / Why

• Scope: (one sentence)
• Non-goals: (explicitly list what's NOT included)

SSOT Contract Impact

• No SSOT change (constants/thresholds/error codes unchanged)
• SSOT changed → fill below:
  • Changed:
  • Migration: (none / snapshot update / doc update)
  • Backward compatible: (yes/no)

Verification

• swift build passed
• swift test passed (or filtered tests)

Anti-rot Gates

• No fatalError / preconditionFailure in Core/
• No magic numbers outside Core/Constants/
• New error codes registered + tested

Key Files Changed