feat(helm): allow A2A base URL to be set when installing

[onematchfox]

Closes #1125

[Copilot]

Pull request overview

This PR adds the ability to configure the A2A (Agent-to-Agent) base URL via Helm chart values, addressing issue #1125. This allows users to specify how the controller service should be addressed by clients connecting to the A2A Server endpoint.

Key Changes:

• Added a2aBaseUrl configuration parameter to the controller section in values.yaml
• Configured the A2A_BASE_URL environment variable in the controller ConfigMap
• Added comprehensive tests to verify both default and custom URL configurations

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
helm/kagent/values.yaml	Adds a2aBaseUrl configuration parameter with default value and documentation
helm/kagent/templates/controller-configmap.yaml	Exposes the A2A base URL as an environment variable to the controller
helm/kagent/tests/controller-deployment_test.yaml	Adds tests for default and custom A2A base URL values

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[onematchfox]

Linting is failing on a change that was part of #1154.

[EItanya]

Linting is failing on a change that was part of #1154.

Super weird, do you mind fixing it quick and then we can merge this

Later edit: #1165 shouid fix this 🤞

[onematchfox]

Later edit: #1165 shouid fix this 🤞

Thanks. Rebased so hopefully everything passes now.