Align onboarding docs and App Insights discovery

[placerda]

Summary

• refine the Foundry prompt/hosted/tutorial onboarding flow and workflow summary guidance
• make Doctor azure_monitor fall back to App Insights ApplicationId from connection string or Foundry telemetry discovery
• update tests and changelog for the new Doctor telemetry path

Validation

• python -m pytest tests\ -x -q
• git --no-pager diff --check

[placerda]

Merged to develop after CI passed. Validation used locally: python -m pytest tests\ -x -q, $env:UV_NO_PROGRESS='1'; uv run mypy src\agentops\ --ignore-missing-imports --show-error-codes, and git --no-pager diff --check.