perf: migrate vsss from k256 to arkworks (#54)

- port the verifiable secret sharing implementation onto arkworks
- `cac::tests::test_full_flow` runtime dropped 1.591s -> 0.162s (~9.8x faster)
- move bitcoin staff into tests-only

Author: cyphersnake

Cargo.lock

@@ -51,9 +51,9 @@ thiserror = "2.0.12"
 serde_json = "1.0"
 serde = { version = "1.0.225", features = ["derive"] }
 ark-serialize = "0.5.0"
+ark-secp256k1 = "0.5.0"
 
 bitcoin = { version = "0.32.7", features = ["rand", "rand-std"] }
-k256 = "0.13.4"
 sha2 = "0.10.9"
 
 [dev-dependencies]
@@ -63,6 +63,7 @@ serde_json = "1.0"
 test-log = { version = "0.2.8", default-features = false, features = ["trace"] }
 bitcoin-script = { git = "https://github.com/BitVM/rust-bitcoin-script" }
 bitvm = { git = "https://github.com/BitVM/BitVM", branch = "main" }
+k256 = "0.13.4"
 
 # Install Git hooks via cargo-husky
 [dev-dependencies.cargo-husky]