Update dependencies and refactor conversation key generation

- Added `github.com/ebitengine/purego` as a direct dependency to the project.
- Removed the unused `p8k.mleku.dev` dependency from the `go.mod` file.
- Refactored the `GenerateConversationKeyFromHex` function to clarify parameter order, aligning with the NIP-44 specification.
- Enhanced test cases for conversation key generation to ensure proper handling of public key formats and improved error messages.
- Updated the `Signer` interface to include methods for extracting and serializing public keys in compressed format.

go.mod

@@ -6,6 +6,7 @@ require (
 	github.com/adrg/xdg v0.5.3
 	github.com/davecgh/go-spew v1.1.1
 	github.com/dgraph-io/badger/v4 v4.8.0
+	github.com/ebitengine/purego v0.9.1
 	github.com/gorilla/websocket v1.5.3
 	github.com/kardianos/osext v0.0.0-20190222173326-2bc1f35cddc0
 	github.com/minio/sha256-simd v1.0.1
@@ -22,7 +23,6 @@ require (
 	honnef.co/go/tools v0.6.1
 	lol.mleku.dev v1.0.5
 	lukechampine.com/frand v1.5.1
-	p8k.mleku.dev v1.0.0
 )
 
 require (
@@ -30,7 +30,6 @@ require (
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/dgraph-io/ristretto/v2 v2.3.0 // indirect
 	github.com/dustin/go-humanize v1.0.1 // indirect
-	github.com/ebitengine/purego v0.9.1 // indirect
 	github.com/felixge/fgprof v0.9.5 // indirect
 	github.com/go-logr/logr v1.4.3 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect