fix: simplify SVG icon for activity bar compatibility

[roomote]

Related GitHub Issue

Closes: #10917

Description

This PR attempts to address Issue #10917 where the activity bar icon does not appear after installation on some Windows environments with newer VS Code versions.

Changes made:

• Removed XML declaration ()
• Removed Adobe Illustrator namespace (xmlns:i)
• Removed internal stylesheet (<defs> and <style> block)
• Changed fill from hardcoded #000 (via CSS class) to fill="currentColor" directly on the path element

Using currentColor instead of a hardcoded color follows VS Code best practices for activity bar icons, allowing the icon to properly adapt to VS Code's theming system and potentially resolving rendering issues in newer VS Code versions.

Test Procedure

1. Build and install the extension in VS Code (particularly v1.108+ on Windows 11)
2. Verify the Roo Code icon appears in the activity bar
3. Verify the icon adapts correctly to light/dark themes

Since this is a pure SVG file change that simplifies the icon structure, there are no automated tests to run. Manual verification is required.

Pre-Submission Checklist

• Issue Linked: This PR is linked to an approved GitHub Issue
• Scope: My changes are focused on the linked issue
• Self-Review: I have performed a thorough self-review of my code
• Testing: Manual testing required on Windows with VS Code v1.108+
• Documentation Impact: No documentation updates required
• Contribution Guidelines: I have read and agree to the Contributor Guidelines

Documentation Updates

• No documentation updates are required.

Additional Notes

This is an attempt to fix the issue. Feedback and guidance are welcome. The changes follow VS Code's recommendations for activity bar icons:

• Simple SVG structure without complex features
• Using currentColor for proper theme integration
• Removing unnecessary metadata and namespaces

[roomote]

Rooviewer   See task on Roo Cloud

Review complete. No issues found.

The changes follow VS Code best practices for activity bar icons: using currentColor for proper theme integration, removing unnecessary XML declarations and Adobe-specific namespaces, and simplifying the SVG structure while preserving the icon path data.

_{Mention @roomote in a comment to request specific changes to this pull request or fix all unresolved issues.}