feat(chainfire): Add /admin/member/add legacy endpoint for cluster join

- AddMemberRequestLegacy accepts string node ID (e.g., 'node01')
- string_to_node_id converts to numeric node_id for Raft
- Required by first-boot-automation.nix cluster join logic
- Also fixes axum 0.8 route syntax (:param -> {param})

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

chainfire/crates/chainfire-server/src/rest.rs

@@ -116,6 +116,15 @@ pub struct AddMemberRequest {
     pub raft_addr: String,
 }
 
+/// Add member request (legacy format from first-boot-automation)
+/// Accepts string id and converts to numeric node_id
+#[derive(Debug, Deserialize)]
+pub struct AddMemberRequestLegacy {
+    /// Node ID as string (e.g., "node01", "node02")
+    pub id: String,
+    pub raft_addr: String,
+}
+
 /// Query parameters for prefix scan
 #[derive(Debug, Deserialize)]
 pub struct PrefixQuery {
@@ -125,12 +134,14 @@ pub struct PrefixQuery {
 /// Build the REST API router
 pub fn build_router(state: RestApiState) -> Router {
     Router::new()
-        .route("/api/v1/kv/:key", get(get_kv))
-        .route("/api/v1/kv/:key", put(put_kv))
-        .route("/api/v1/kv/:key", delete(delete_kv))
+        .route("/api/v1/kv/{key}", get(get_kv))
+        .route("/api/v1/kv/{key}", put(put_kv))
+        .route("/api/v1/kv/{key}", delete(delete_kv))
         .route("/api/v1/kv", get(list_kv))
         .route("/api/v1/cluster/status", get(cluster_status))
         .route("/api/v1/cluster/members", post(add_member))
+        // Legacy endpoint for first-boot-automation compatibility
+        .route("/admin/member/add", post(add_member_legacy))
         .route("/health", get(health_check))
         .with_state(state)
 }
@@ -258,6 +269,22 @@ async fn cluster_status(
     })))
 }
 
+/// Convert string node ID to numeric (e.g., "node01" -> 1, "node02" -> 2)
+fn string_to_node_id(s: &str) -> u64 {
+    // Try to extract number from string like "node01", "node02"
+    if let Some(num_str) = s.strip_prefix("node") {
+        if let Ok(num) = num_str.parse::<u64>() {
+            return num;
+        }
+    }
+    // Fallback: use hash of the string
+    use std::collections::hash_map::DefaultHasher;
+    use std::hash::{Hash, Hasher};
+    let mut hasher = DefaultHasher::new();
+    s.hash(&mut hasher);
+    hasher.finish()
+}
+
 /// POST /api/v1/cluster/members - Add member
 async fn add_member(
     State(state): State<RestApiState>,
@@ -286,6 +313,33 @@ async fn add_member(
     ))
 }
 
+/// POST /admin/member/add - Add member (legacy format for first-boot-automation)
+async fn add_member_legacy(
+    State(state): State<RestApiState>,
+    Json(req): Json<AddMemberRequestLegacy>,
+) -> Result<(StatusCode, Json<SuccessResponse<serde_json::Value>>), (StatusCode, Json<ErrorResponse>)> {
+    let node_id = string_to_node_id(&req.id);
+
+    let rpc_client = state
+        .rpc_client
+        .as_ref()
+        .ok_or_else(|| error_response(StatusCode::SERVICE_UNAVAILABLE, "SERVICE_UNAVAILABLE", "RPC client not available"))?;
+
+    // Add node to RPC client's routing table
+    rpc_client.add_node(node_id, req.raft_addr.clone()).await;
+
+    Ok((
+        StatusCode::CREATED,
+        Json(SuccessResponse::new(serde_json::json!({
+            "id": req.id,
+            "node_id": node_id,
+            "raft_addr": req.raft_addr,
+            "success": true,
+            "note": "Node registered in RPC client routing table (legacy API)"
+        }))),
+    ))
+}
+
 /// Helper to create error response
 fn error_response(
     status: StatusCode,