[Phase 1a] Implement prompt matching and retry logic

[usepowershell]

Part of #98

Implement the logic to match incoming snapshots to current prompts and inject responses.

Subtasks

• Design prompt matching algorithm
• Implement PromptMatcher class
• Implement state injection into PSHost when snapshot provided
• Handle PromptId isolation for concurrent requests
• Add timeout handling (5 min max)
• Unit tests
• Integration tests

Effort: 1 week