feat(ffi): add dash_spv_ffi_config_clear_peers (#591)

* feat(ffi): add dash_spv_ffi_config_clear_peers to remove default peers

When creating an SPV config for regtest, a default peer at
127.0.0.1:19899 is added. This doesn't match dashmate's Docker
setup which maps Core P2P to different ports (e.g. 20001). FFI
consumers (iOS/Swift) couldn't clear these defaults before adding
their own peers, causing the SPV client to enter exclusive mode
with a dead peer alongside the intended one.

Adds dash_spv_ffi_config_clear_peers() so FFI consumers can remove
default peers before adding custom ones via add_peer.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore: regenerate FFI docs and apply fmt

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* test: add unit tests for dash_spv_ffi_config_clear_peers

Tests cover:
- clearing peers after adding multiple peers
- clearing an already-empty peer list succeeds
- null pointer returns NullPointer error code

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: QuantumExplorer

dash-spv-ffi/FFI_API.md

@@ -4,7 +4,7 @@ This document provides a comprehensive reference for all FFI (Foreign Function I
 
 **Auto-generated**: This documentation is automatically generated from the source code. Do not edit manually.
 
-**Total Functions**: 40
+**Total Functions**: 41
 
 ## Table of Contents
 
@@ -31,12 +31,13 @@ Functions: 3
 
 ### Configuration
 
-Functions: 16
+Functions: 17
 
 | Function | Description | Module |
 |----------|-------------|--------|
 | `dash_spv_ffi_client_update_config` | Update the running client's configuration | client |
 | `dash_spv_ffi_config_add_peer` | Adds a peer address to the configuration  Accepts socket addresses with or... | config |
+| `dash_spv_ffi_config_clear_peers` | Removes all configured peers from the configuration  This is useful when the... | config |
 | `dash_spv_ffi_config_destroy` | Destroys an FFIClientConfig and frees its memory  # Safety - `config` must... | config |
 | `dash_spv_ffi_config_get_network` | Gets the network type from the configuration  # Safety - `config` must be a... | config |
 | `dash_spv_ffi_config_mainnet` | No description | config |
@@ -201,6 +202,22 @@ Adds a peer address to the configuration  Accepts socket addresses with or witho
 
 ---
 
+#### `dash_spv_ffi_config_clear_peers`
+
+```c
+dash_spv_ffi_config_clear_peers(config: *mut FFIClientConfig) -> i32
+```
+
+**Description:**
+Removes all configured peers from the configuration  This is useful when the caller wants to start with a clean slate before adding custom peers via `dash_spv_ffi_config_add_peer`.  # Safety - `config` must be a valid pointer to an FFIClientConfig created by dash_spv_ffi_config_new/mainnet/testnet - The caller must ensure the config pointer remains valid for the duration of this call
+
+**Safety:**
+- `config` must be a valid pointer to an FFIClientConfig created by dash_spv_ffi_config_new/mainnet/testnet - The caller must ensure the config pointer remains valid for the duration of this call
+
+**Module:** `config`
+
+---
+
 #### `dash_spv_ffi_config_destroy`
 
 ```c

dash-spv-ffi/src/config.rs

@@ -166,6 +166,23 @@ pub unsafe extern "C" fn dash_spv_ffi_config_add_peer(
     }
 }
 
+/// Removes all configured peers from the configuration
+///
+/// This is useful when the caller wants to start with a clean slate
+/// before adding custom peers via `dash_spv_ffi_config_add_peer`.
+///
+/// # Safety
+/// - `config` must be a valid pointer to an FFIClientConfig created by dash_spv_ffi_config_new/mainnet/testnet
+/// - The caller must ensure the config pointer remains valid for the duration of this call
+#[no_mangle]
+pub unsafe extern "C" fn dash_spv_ffi_config_clear_peers(config: *mut FFIClientConfig) -> i32 {
+    null_check!(config);
+
+    let cfg = unsafe { &mut *((*config).inner as *mut ClientConfig) };
+    cfg.peers.clear();
+    FFIErrorCode::Success as i32
+}
+
 /// Sets the user agent string to advertise in the P2P handshake
 ///
 /// # Safety

dash-spv-ffi/tests/test_config.rs

@@ -94,6 +94,39 @@ mod tests {
         }
     }
 
+    #[test]
+    #[serial]
+    fn test_config_clear_peers() {
+        unsafe {
+            let config = dash_spv_ffi_config_new(FFINetwork::Testnet);
+
+            // Add peers
+            let peer1 = CString::new("127.0.0.1:9999").unwrap();
+            let peer2 = CString::new("127.0.0.2:9999").unwrap();
+            dash_spv_ffi_config_add_peer(config, peer1.as_ptr());
+            dash_spv_ffi_config_add_peer(config, peer2.as_ptr());
+
+            // Clear all peers
+            let result = dash_spv_ffi_config_clear_peers(config);
+            assert_eq!(result, FFIErrorCode::Success as i32);
+
+            // Clear on already-empty should still succeed
+            let result = dash_spv_ffi_config_clear_peers(config);
+            assert_eq!(result, FFIErrorCode::Success as i32);
+
+            dash_spv_ffi_config_destroy(config);
+        }
+    }
+
+    #[test]
+    #[serial]
+    fn test_config_clear_peers_null() {
+        unsafe {
+            let result = dash_spv_ffi_config_clear_peers(std::ptr::null_mut());
+            assert_eq!(result, FFIErrorCode::NullPointer as i32);
+        }
+    }
+
     #[test]
     #[serial]
     fn test_config_user_agent() {