feat: add new user agent: foundry_agent_canvas

[qinezh]

Summary

• recognize foundry_agent_canvas in AZURE_DEV_USER_AGENT
• append Foundry Agent Canvas to the existing execution.environment base value
• extend unit and functional telemetry verification and document the modifier

Foundry Agent Canvas is a GitHub Copilot App Extension that helps developers create, configure, test, and deploy a hosted agent. It’s already available in the awesome-copilot marketplace. It uses the azd command for some user actions, and we’d like to track usage of the azd command from Foundry Agent Canvas.

Fix #9207

[azure-pipelines]

Azure Pipelines:
7 pipeline(s) were filtered out due to trigger conditions.
There may be pipelines that require an authorized user to comment /azp run to run.

[microsoft-github-policy-service]

Thank you for your contribution @qinezh! We will review the pull request and get back to you soon.

[Copilot]

Pull request overview

Adds Foundry Agent Canvas attribution to azd execution-environment telemetry.

Changes:

• Detects foundry_agent_canvas in the user agent.
• Adds unit and functional verification.
• Documents the telemetry modifier.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
docs/reference/telemetry-data.md	Documents the modifier.
cli/azd/test/functional/telemetry_test.go	Verifies emitted telemetry.
cli/azd/internal/tracing/resource/resource_test.go	Adds modifier unit tests.
cli/azd/internal/tracing/resource/exec_environment.go	Detects the user-agent token.
cli/azd/internal/tracing/fields/fields.go	Defines the modifier value.

[jongio]

Follows the established modifier pattern exactly, with matching unit and functional tests plus a doc update. The append order in the test lines up with the detection order in execEnvModifiers.

On the bot's canonical-schema comment: your won't fix is right. telemetry-schema.md describes execution.environment only as CI system detection and does not enumerate the existing modifiers, so there is nothing to sync here.