Add opt-in Timberlogs diagnostics

[enaboapps]

Closes #435

Summary

• add opt-in Timberlogs crash, exception, and app-health reporting using an install-scoped random ID
• redact secrets and Windows user paths, bound offline crash reports, and purge queued data on opt-out
• add one-time consent, a fifth setup step, and Settings > Privacy controls
• inject the API key at build time and fail release packaging when the secret is unavailable
• bump Switchify PC to 0.6.4

Verification

• dotnet restore src/SwitchifyPc.sln
• dotnet build src/SwitchifyPc.sln -c Release --no-restore
• dotnet test src/SwitchifyPc.sln -c Release --no-build (423 unit/UI + 1 integration)
• signed scripts/Package-Windows.ps1
• scripts/Verify-DotnetPackage.ps1
• scripts/Verify-UpdaterMetadata.ps1
• manual WPF smoke: launch, consent dialog, five-step setup, Settings > Privacy
• privacy/FAQ disclosure merged and verified in enaboapps/switchify-website#6

Release gate

The workflow requires TIMBERLOGS_API_KEY. Organization-secret creation is pending an org-admin/Actions-secrets permission for the current GitHub CLI login.