Add error reporting for invalid credentials and move google service account b64 to plug config

[shivankacker]

No description provided.

[Copilot]

Pull request overview

This PR improves configuration and failure visibility for the Google GenAI/Vertex AI scribe provider by moving the Google service-account base64 credential into plugin settings and surfacing clearer initialization errors in the scribe processing task.

Changes:

• Read Google service-account credentials from plugin_settings instead of os.getenv, with explicit error messages for base64/JSON/key parsing failures.
• Wrap AI client initialization in process_ai_form_fill with error capture that marks the scribe as failed and records the error in form.meta.processings.
• Add SCRIBE_GOOGLE_APPLICATION_CREDENTIALS_B64 to plugin settings defaults.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
care_scribe/tasks/scribe.py	Adds robust credential decoding/parsing errors and persists AI-client init failures into scribe processing metadata.
care_scribe/settings.py	Adds a default config entry for SCRIBE_GOOGLE_APPLICATION_CREDENTIALS_B64 so it can be provided via plugin config/env.

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