feat: README, config.example, turnstile integration, exchange rate, auth utils refactor

src/queue/handler/mod.rs

@@ -77,11 +77,17 @@ pub fn register_all(repos: Arc<Repositories>, config: Arc<Config>) -> ServeMux {
         },
     );
 
-    // ── Quota task ────────────────────────────────────────────────────────────
+    // ── Quota task + Rate task ─────────────────────────────────────────────────
     let quota_repos = Arc::clone(&repos);
     let quota_config = Arc::clone(&config);
-    mux.handle_async_func(crate::queue::types::FORTHWITH_QUOTA_TASK, move |task| {
-        task::quota_task(task, Arc::clone(&quota_repos), Arc::clone(&quota_config))
+    mux.handle_async_func(crate::queue::types::FORTHWITH_QUOTA_TASK, move |t| {
+        task::quota_task(t, Arc::clone(&quota_repos), Arc::clone(&quota_config))
+    });
+
+    let rate_repos = Arc::clone(&repos);
+    let rate_config = Arc::clone(&config);
+    mux.handle_async_func(crate::queue::types::FORTHWITH_RATE_TASK, move |t| {
+        task::rate_task(t, Arc::clone(&rate_repos), Arc::clone(&rate_config))
     });
 
     mux

src/queue/handler/task.rs

@@ -4,7 +4,7 @@ use asynq::error::Result;
 use asynq::task::Task;
 
 use crate::config::Config;
-use crate::queue::service::task::QuotaTaskLogic;
+use crate::queue::service::task::{QuotaTaskLogic, RateLogic};
 use crate::repository::Repositories;
 
 pub async fn quota_task(task: Task, repos: Arc<Repositories>, config: Arc<Config>) -> Result<()> {
@@ -13,3 +13,12 @@ pub async fn quota_task(task: Task, repos: Arc<Repositories>, config: Arc<Config
         .await
         .map_err(|e| asynq::error::Error::other(e.to_string()))
 }
+
+/// Fetch the current exchange rate and persist it.
+/// Scheduled daily at 01:00 by the scheduler (mirrors `rateLogic.go`).
+pub async fn rate_task(_task: Task, repos: Arc<Repositories>, config: Arc<Config>) -> Result<()> {
+    RateLogic::new(repos, config)
+        .execute()
+        .await
+        .map_err(|e| asynq::error::Error::other(e.to_string()))
+}

src/queue/service/task.rs

@@ -250,3 +250,57 @@ impl QuotaTaskLogic {
         Ok(())
     }
 }
+
+// ─────────────────────────────────────────────────────────────────────────────
+// RateLogic — port of `server/queue/logic/task/rateLogic.go`
+// Fetches the current exchange rate for the site currency and caches it.
+// ─────────────────────────────────────────────────────────────────────────────
+
+pub struct RateLogic {
+    repos: Arc<Repositories>,
+    config: Arc<Config>,
+}
+
+impl RateLogic {
+    pub fn new(repos: Arc<Repositories>, config: Arc<Config>) -> Self {
+        Self { repos, config }
+    }
+
+    /// Fetch exchange rate from apilayer.com and cache it in Redis.
+    ///
+    /// Skips silently when `Currency.AccessKey` is not configured.
+    pub async fn execute(&self) -> anyhow::Result<()> {
+        let access_key = &self.config.currency.access_key;
+        if access_key.is_empty() {
+            tracing::debug!("[RateLogic] skip: no Currency.AccessKey configured");
+            return Ok(());
+        }
+
+        let from = &self.config.currency.unit;
+        if from.is_empty() || from.to_uppercase() == "CNY" {
+            // Already in base currency — rate is 1.0, nothing to fetch.
+            tracing::debug!("[RateLogic] skip: currency unit is CNY or empty");
+            return Ok(());
+        }
+
+        match crate::exchange_rate::convert(from, "CNY", 1.0, access_key).await {
+            Ok(rate) => {
+                tracing::info!(
+                    "[RateLogic] exchange rate {from}→CNY = {rate:.6}"
+                );
+                // Persist rate to system config table.
+                let _ = self
+                    .repos
+                    .system
+                    .update_value_by_category_key("currency", "exchange_rate", &rate.to_string())
+                    .await
+                    .map_err(|e| tracing::warn!("[RateLogic] persist rate failed: {e}"));
+            }
+            Err(e) => {
+                tracing::error!("[RateLogic] fetch exchange rate failed: {e}");
+                return Err(e);
+            }
+        }
+        Ok(())
+    }
+}

src/queue/types.rs

@@ -28,3 +28,5 @@ pub const FORTHWITH_TRAFFIC_STATISTICS: &str = "forthwith:traffic:statistics";
 
 // ── task / quota ───────────────────────────────────────────────────────
 pub const FORTHWITH_QUOTA_TASK: &str = "forthwith:quota:task";
+/// Daily exchange-rate refresh (mirrors Go `ForthwithRateTask`).
+pub const FORTHWITH_RATE_TASK: &str = "forthwith:rate:task";