💎 fix: Gemini Image Gen Tool Vertex AI Auth and File Storage (#11923)

* chore: saveToCloudStorage function and enhance error handling

- Removed unnecessary parameters and streamlined the logic for saving images to cloud storage.
- Introduced buffer handling for base64 image data and improved the integration with file strategy functions.
- Enhanced error handling during local image saving to ensure robustness.
- Updated the createGeminiImageTool function to reflect changes in the saveToCloudStorage implementation.

* refactor: streamline image persistence logic in GeminiImageGen

- Consolidated image saving functionality by renaming and refactoring the saveToCloudStorage function to persistGeneratedImage.
- Improved error handling and logging for image persistence operations.
- Enhanced the replaceUnwantedChars function to better sanitize input strings.
- Updated createGeminiImageTool to reflect changes in image handling and ensure consistent behavior across storage strategies.

* fix: clean up GeminiImageGen by removing unused functions and improving logging

- Removed the getSafeFormat and persistGeneratedImage functions to streamline image handling.
- Updated logging in createGeminiImageTool for clarity and consistency.
- Consolidated imports by eliminating unused dependencies, enhancing code maintainability.

* chore: update environment configuration and manifest for unused GEMINI_VERTEX_ENABLED

- Removed the Vertex AI configuration option from .env.example to simplify setup.
- Updated the manifest.json to reflect the removal of the Vertex AI dependency in the authentication field.
- Cleaned up the createGeminiImageTool function by eliminating unused fields related to Vertex AI, streamlining the code.

* fix: update loadAuthValues call in loadTools function for GeminiImageGen tool

- Modified the loadAuthValues function call to include throwError: false, preventing exceptions on authentication failures.
- Removed the unused processFileURL parameter from the tool context object, streamlining the code.

* refactor: streamline GoogleGenAI initialization in GeminiImageGen

- Removed unused file system access check for Google application credentials, simplifying the environment setup.
- Added googleAuthOptions to the GoogleGenAI instantiation, enhancing the configuration for authentication.

* fix: update Gemini API Key label and description in manifest.json

- Changed the label to indicate that the Gemini API Key is optional.
- Revised the description to clarify usage with Vertex AI and service accounts, enhancing user guidance.

* fix: enhance abort signal handling in createGeminiImageTool

- Introduced derivedSignal to manage abort events during image generation, improving responsiveness to cancellation requests.
- Added an abortHandler to log when image generation is aborted, enhancing debugging capabilities.
- Ensured proper cleanup of event listeners in the finally block to prevent memory leaks.

* fix: update authentication handling for plugins to support optional fields

- Added support for optional authentication fields in the manifest and PluginAuthForm.
- Updated the checkPluginAuth function to correctly validate plugins with optional fields.
- Enhanced tests to cover scenarios with optional authentication fields, ensuring accurate validation logic.

.env.example

@@ -243,10 +243,6 @@ GOOGLE_KEY=user_provided
 # Option A: Use dedicated Gemini API key for image generation
 # GEMINI_API_KEY=your-gemini-api-key
 
-# Option B: Use Vertex AI (no API key needed, uses service account)
-# Set this to enable Vertex AI and allow tool without requiring API keys
-# GEMINI_VERTEX_ENABLED=true
-
 # Vertex AI model for image generation (defaults to gemini-2.5-flash-image)
 # GEMINI_IMAGE_MODEL=gemini-2.5-flash-image