[Cryptoom]

Summary

• Adds UpdateWorkspaceTool, a new MCP tool that writes the current workspace's brand settings (name, brand_website, brand_description, brand_voice_traits, brand_color, background_color, text_color, brand_font, image_style, content_language). GetWorkspaceTool was read only, there was no API/MCP path to write these fields.
• PATCH semantics: every field is optional, only the fields actually passed are validated and written. Validation mirrors UpdateWorkspaceRequest.
• Authorization mirrors the settings UI: AuthorizesMcpTool::authorizeCurrentWorkspace($request, 'update', ...), same WorkspacePolicy::update ability as WorkspaceController::updateSettings().
• Registered in TryPostServer under the existing "Workspace" section.
• Documented as fork Patch 1 in PATCHES.md (this repo is AGPL-3.0, patches are tracked so a future upstream merge does not silently clobber it).

Test plan

• tests/Feature/Mcp/WorkspaceToolTest.php: 4 new tests (valid partial update, invalid brand_color rejected, cannot touch another workspace, member without Admin/Owner role denied).
• php artisan test tests/Feature/Mcp, 190/190 passing.
• Verified no unintended file changes (git status --short before commit only shows the 4 intended files).

No changes to UpdateWorkspaceRequest, WorkspacePolicy, or any other existing tool/validation logic.