Update go version matrices for CI/CD workflows

Update README and usage docs to with new default DB file path

Replace BadgerDB with bbolt

Remove database mocks, replace `Service` interface indirection

Update copyright footer

Remove Tines as sponsor

Add HTTP header support to string literal matching

Rename `search` package to `filter` package

Add filter support for HTTP headers

Sort HTTP headers

Add "New request" button to Sender page

Add new sponsorship options

Publish Docker image to ghcr.io and docker.io

Add intercept feature to README

Update admin dependencies