Add Version Guard scan and snapshot RCA telemetry

[revied]

🤖

Summary

• add collector scan trigger, per-resource detection, and snapshot validation metrics
• mark full vs targeted scans so full snapshots validate expected resource families before persistence
• fail full-scan snapshot creation when an expected resource type is missing, while allowing targeted scans
• record expected/present resource-family gauges and last valid snapshot timestamp

Tests

• go test ./...
• go vet ./...
• golangci-lint run --timeout=5m