Replace lunr in Search & Tag Filtering

[CodeSpent]

Lunr unfortunately doesn't appear to be maintained any further & thus I need to move away from it. ContentLayer.dev is what's being used for MDX content now, which appears to include an index.

Will need to investigate options for handling searching that's both easy to implement, robust, & scalable as Search & Filter will be first-class-citizens in the overall repurposing of this project (ie Resume, DevStreams, etc will also use these utilities & patterns).