safety: remove hardcoded dev credentials, add clippy deny to broker_gateway

- api_gateway: DATABASE_URL now required (was fallback to hardcoded dev password)
- broker_gateway: DATABASE_URL now required (was fallback to hardcoded dev password)
- broker_gateway: add deny(clippy::unwrap_used, clippy::expect_used) to lib.rs

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

services/api_gateway/src/main.rs

@@ -235,9 +235,8 @@ async fn main() -> Result<()> {
     };
 
     // Initialize configuration manager (requires database)
-    let database_url = std::env::var("DATABASE_URL").unwrap_or_else(|_| {
-        "postgresql://foxhunt:foxhunt_dev_password@localhost:5432/foxhunt".to_string()
-    });
+    let database_url = std::env::var("DATABASE_URL")
+        .map_err(|_| anyhow::anyhow!("DATABASE_URL environment variable must be set"))?;
     let db_pool = sqlx::PgPool::connect(&database_url)
         .await
         .map_err(|e| anyhow::anyhow!("Failed to connect to database: {}", e))?;

services/broker_gateway_service/src/lib.rs

@@ -3,6 +3,7 @@
 //! Provides broker connectivity for order routing via FIX protocol.
 
 #![deny(warnings)]
+#![deny(clippy::unwrap_used, clippy::expect_used)]
 
 pub mod proto {
     pub mod broker_gateway {

services/broker_gateway_service/src/main.rs

@@ -32,7 +32,7 @@ async fn main() -> Result<()> {
 
     // Get database URL from environment
     let database_url = std::env::var("DATABASE_URL")
-        .unwrap_or_else(|_| "postgresql://foxhunt:foxhunt_dev_password@localhost:5432/foxhunt".to_string());
+        .context("DATABASE_URL environment variable must be set")?;
 
     // Initialize database pool
     let db_pool = PgPool::connect(&database_url)