Feat/pricing config enhancement (#781)

* feat(db): add pricing config fields to proxy_config table

- Add default_cost_multiplier field per app type
- Add pricing_model_source field (request/response)
- Add request_model field to proxy_request_logs table
- Implement schema migration v5

* feat(api): add pricing config commands and provider meta fields

- Add get/set commands for default cost multiplier
- Add get/set commands for pricing model source
- Extend ProviderMeta with cost_multiplier and pricing_model_source
- Register new commands in Tauri invoke handler

* fix(proxy): apply cost multiplier to total cost only

- Move multiplier calculation from per-item to total cost
- Add resolve_pricing_config for provider-level override
- Include request_model and cost_multiplier in usage logs
- Return new fields in get_request_logs API

* feat(ui): add pricing config UI and usage log enhancements

- Add pricing config section to provider advanced settings
- Refactor PricingConfigPanel to compact table layout
- Display all three apps (Claude/Codex/Gemini) in one view
- Add multiplier column and request model display to logs
- Add frontend API wrappers for pricing config

* feat(i18n): add pricing config translations

- Add zh/en/ja translations for pricing defaults config
- Add translations for multiplier, requestModel, responseModel
- Add provider pricing config translations

* fix(pricing): align backfill cost calculation with real-time logic

- Fix backfill to deduct cache_read_tokens from input (avoid double billing)
- Apply multiplier only to total cost, not to each item
- Add multiplier display in request detail panel with i18n support
- Use AppError::localized for backend error messages
- Fix init_proxy_config_rows to use per-app default values
- Fix silent failure in set_default_cost_multiplier/set_pricing_model_source
- Add clippy allow annotation for test mutex across await

* style: format code with cargo fmt and prettier

* fix(tests): correct error type assertions in proxy DAO tests

The tests expected AppError::InvalidInput but the DAO functions use
AppError::localized() which returns AppError::Localized variant.
Updated assertions to match the correct error type with key validation.

---------

Co-authored-by: Jason <farion1231@gmail.com>

src-tauri/tests/proxy_commands.rs

@@ -0,0 +1,78 @@
+use cc_switch_lib::{
+    get_default_cost_multiplier_test_hook, get_pricing_model_source_test_hook,
+    set_default_cost_multiplier_test_hook, set_pricing_model_source_test_hook, AppError,
+};
+
+#[path = "support.rs"]
+mod support;
+use support::{create_test_state, ensure_test_home, reset_test_fs, test_mutex};
+
+// 测试使用 Mutex 进行串行化，跨 await 持锁是预期行为
+#[allow(clippy::await_holding_lock)]
+#[tokio::test]
+async fn default_cost_multiplier_commands_round_trip() {
+    let _guard = test_mutex().lock().expect("acquire test mutex");
+    reset_test_fs();
+    let _home = ensure_test_home();
+
+    let state = create_test_state().expect("create test state");
+
+    let default = get_default_cost_multiplier_test_hook(&state, "claude")
+        .await
+        .expect("read default multiplier");
+    assert_eq!(default, "1");
+
+    set_default_cost_multiplier_test_hook(&state, "claude", "1.5")
+        .await
+        .expect("set multiplier");
+    let updated = get_default_cost_multiplier_test_hook(&state, "claude")
+        .await
+        .expect("read updated multiplier");
+    assert_eq!(updated, "1.5");
+
+    let err = set_default_cost_multiplier_test_hook(&state, "claude", "not-a-number")
+        .await
+        .expect_err("invalid multiplier should error");
+    // 错误已改为 Localized 类型（支持 i18n）
+    match err {
+        AppError::Localized { key, .. } => {
+            assert_eq!(key, "error.invalidMultiplier");
+        }
+        other => panic!("expected localized error, got {other:?}"),
+    }
+}
+
+// 测试使用 Mutex 进行串行化，跨 await 持锁是预期行为
+#[allow(clippy::await_holding_lock)]
+#[tokio::test]
+async fn pricing_model_source_commands_round_trip() {
+    let _guard = test_mutex().lock().expect("acquire test mutex");
+    reset_test_fs();
+    let _home = ensure_test_home();
+
+    let state = create_test_state().expect("create test state");
+
+    let default = get_pricing_model_source_test_hook(&state, "claude")
+        .await
+        .expect("read default pricing model source");
+    assert_eq!(default, "response");
+
+    set_pricing_model_source_test_hook(&state, "claude", "request")
+        .await
+        .expect("set pricing model source");
+    let updated = get_pricing_model_source_test_hook(&state, "claude")
+        .await
+        .expect("read updated pricing model source");
+    assert_eq!(updated, "request");
+
+    let err = set_pricing_model_source_test_hook(&state, "claude", "invalid")
+        .await
+        .expect_err("invalid pricing model source should error");
+    // 错误已改为 Localized 类型（支持 i18n）
+    match err {
+        AppError::Localized { key, .. } => {
+            assert_eq!(key, "error.invalidPricingMode");
+        }
+        other => panic!("expected localized error, got {other:?}"),
+    }
+}