Dashboard performance improvements and log search enhancements

This release improves initial page load performance and adds attribute key discovery when searching MCP logs.

Features

• Faster initial page load #2058  - Improved initial page load performance by prefetching key queries in parallel with auth, adding preconnect hints, and switching font-display to swap. (Author: @adaam2 )
• Attribute key discovery in log search #2050  - When searching MCP logs, available attribute keys are now displayed to assist with filtering. (Author: @alx-xo )

Bug fixes

• Idempotent project deletion #2069  - The DeleteProject endpoint now returns idempotent success for non-existent projects instead of a misleading error. (Author: @bflad )
• Fix toolset cache invalidation on template deletion #2046  - Fixed an issue where the toolset cache was not being invalidated when a template was deleted. (Author: @bflad )
• Remove legacy grants API endpoints #2043  - Removed the legacy grants API endpoints, now replaced by the roles management API. (Author: @tgmendes )