refactor!: drop rand dependency from the library

create_psbt no longer needs an RNG (AFS — the only consumer — takes
its own rng explicitly), so the create_psbt_with_rng wrapper and its
thread_rng() call were dead weight. Collapses both into a single
create_psbt(self, params) and moves rand to dev-dependencies.

The library now depends only on rand_core (for the RngCore trait) +
miniscript + bdk_coin_select.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: evanlinjin

Cargo.toml

@@ -18,7 +18,6 @@ unexpected_cfgs = { level = "warn", check-cfg = ['cfg(coverage_nightly)'] }
 bdk_coin_select = { version = "0.4.1" }
 miniscript = { version = "12.3.7", default-features = false }
 rand_core = { version = "0.6.4", default-features = false }
-rand = { version = "0.8", optional = true }
 
 [dev-dependencies]
 anyhow = "1"
@@ -27,6 +26,7 @@ bitcoin = { version = "0.32.10", default-features = false, features = ["rand-std
 bdk_testenv = "0.13.0"
 bdk_bitcoind_rpc = "0.22.0"
 bdk_chain = { version = "0.23.3" }
+rand = "0.8"
 
 [features]
 default = ["std"]

src/tx_template.rs

@@ -385,17 +385,7 @@ impl TxTemplate {
     }
 
     /// Build the [`Psbt`] and its associated [`Finalizer`].
-    #[cfg(feature = "std")]
     pub fn create_psbt(self, params: PsbtBuildParams) -> Result<(Psbt, Finalizer), BuildPsbtError> {
-        self.create_psbt_with_rng(params, &mut rand::thread_rng())
-    }
-
-    /// Build the [`Psbt`] and its associated [`Finalizer`] with a custom `rng`.
-    pub fn create_psbt_with_rng(
-        self,
-        params: PsbtBuildParams,
-        _rng: &mut impl RngCore,
-    ) -> Result<(Psbt, Finalizer), BuildPsbtError> {
         let tx = self.to_unsigned_tx();
         let mut psbt = Psbt::from_unsigned_tx(tx).map_err(BuildPsbtError::Psbt)?;