Update dependencies and refactor p256k crypto package

- Bumped version of lol.mleku.dev from v1.0.4 to v1.0.5.
- Added new dependencies: p256k1.mleku.dev and several indirect dependencies for improved cryptographic functionality.
- Refactored p256k package to utilize p256k1.mleku.dev/signer for signature operations, replacing the previous btcec implementation.
- Removed the secp256k1.go file, consolidating the crypto logic under the new p256k1 library.
- Updated documentation to reflect changes in the signer interface and usage.

go.mod

@@ -20,13 +20,18 @@ require (
 	golang.org/x/lint v0.0.0-20241112194109-818c5a804067
 	golang.org/x/net v0.46.0
 	honnef.co/go/tools v0.6.1
-	lol.mleku.dev v1.0.4
+	lol.mleku.dev v1.0.5
 	lukechampine.com/frand v1.5.1
+	p256k1.mleku.dev v1.0.1
 )
 
 require (
 	github.com/BurntSushi/toml v1.5.0 // indirect
+	github.com/btcsuite/btcd/btcec/v2 v2.3.6 // indirect
+	github.com/btcsuite/btcd/chaincfg/chainhash v1.0.1 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
+	github.com/decred/dcrd/crypto/blake256 v1.0.0 // indirect
+	github.com/decred/dcrd/dcrec/secp256k1/v4 v4.0.1 // indirect
 	github.com/dgraph-io/ristretto/v2 v2.3.0 // indirect
 	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/felixge/fgprof v0.9.5 // indirect
@@ -35,6 +40,7 @@ require (
 	github.com/google/flatbuffers v25.9.23+incompatible // indirect
 	github.com/google/pprof v0.0.0-20251007162407-5df77e3f7d1d // indirect
 	github.com/klauspost/compress v1.18.1 // indirect
+	github.com/minio/sha256-simd v1.0.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/templexxx/cpu v0.1.1 // indirect
 	go.opentelemetry.io/auto/sdk v1.2.1 // indirect