feat: add Universal Provider feature (#348)

* feat: add Universal Provider feature

- Add Universal Provider data structures and type definitions
- Implement backend CRUD operations and sync functionality
- Add frontend UI components (UniversalProviderPanel, Card, FormModal)
- Add NewAPI icon and preset configuration
- Support cross-app (Claude/Codex/Gemini) configuration sync
- Add website URL field for providers
- Implement real-time refresh via event notifications
- Add i18n support (Chinese/English/Japanese)

* feat: integrate universal provider presets into add provider dialog

- Add universal provider presets (NewAPI, Custom Gateway) to preset selector
- Show universal presets with Layers icon badge in preset selector
- Open UniversalProviderFormModal when universal preset is clicked
- Pass initialPreset to auto-fill form when opened from add dialog
- Add i18n keys for addSuccess/addFailed messages
- Keep separate universal provider panel for management

* refactor: move universal provider management to add dialog

- Remove Layers button from main navigation header
- Add 'Manage' button next to universal provider presets
- Open UniversalProviderPanel from within add provider dialog
- Add i18n keys for 'manage' in all locales

* style: display universal provider presets on separate line

- Move universal provider section to a new row with border separator
- Add label '统一供应商:' to clarify the section

* style: unify universal provider label style with preset label

- Use FormLabel component for consistent styling
- Add background to 'Manage' button matching preset buttons
- Update icon size and button padding for consistency

* feat: add sync functionality and JSON preview for Universal Provider

* fix: add missing in_failover_queue field to Provider structs

After rebasing to main, the Provider struct gained a new
`in_failover_queue` field. This fix adds the missing field
to the three to_*_provider() methods in UniversalProvider.

* refactor: redesign AddProviderDialog with tab-based layout

- Add tabs to separate app-specific providers and universal providers
- Move "Add Universal Provider" button from panel header to footer
- Remove unused handleAdd callback and clean up imports
- Update emptyHint i18n text to reference the footer button

* fix: append /v1 suffix to Codex base_url in Universal Provider

Codex uses OpenAI-compatible API which requires the /v1 endpoint suffix.
The Universal Provider now automatically appends /v1 to base_url when
generating Codex provider config if not already present.

- Handle trailing slashes to avoid double slashes
- Apply fix to both backend (to_codex_provider) and frontend preview

* feat: auto-sync universal provider to apps on creation

Previously, users had to manually click sync after adding a universal
provider. Now it automatically syncs to Claude/Codex/Gemini on creation,
providing a smoother user experience.

---------

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

src-tauri/src/services/provider/mod.rs

@@ -690,3 +690,140 @@ pub struct ProviderSortUpdate {
     #[serde(rename = "sortIndex")]
     pub sort_index: usize,
 }
+
+// ============================================================================
+// 统一供应商（Universal Provider）服务方法
+// ============================================================================
+
+use crate::provider::UniversalProvider;
+use std::collections::HashMap;
+
+impl ProviderService {
+    /// 获取所有统一供应商
+    pub fn list_universal(
+        state: &AppState,
+    ) -> Result<HashMap<String, UniversalProvider>, AppError> {
+        state.db.get_all_universal_providers()
+    }
+
+    /// 获取单个统一供应商
+    pub fn get_universal(
+        state: &AppState,
+        id: &str,
+    ) -> Result<Option<UniversalProvider>, AppError> {
+        state.db.get_universal_provider(id)
+    }
+
+    /// 添加或更新统一供应商（不自动同步，需手动调用 sync_universal_to_apps）
+    pub fn upsert_universal(
+        state: &AppState,
+        provider: UniversalProvider,
+    ) -> Result<bool, AppError> {
+        // 保存统一供应商
+        state.db.save_universal_provider(&provider)?;
+
+        Ok(true)
+    }
+
+    /// 删除统一供应商
+    pub fn delete_universal(state: &AppState, id: &str) -> Result<bool, AppError> {
+        // 获取统一供应商（用于删除生成的子供应商）
+        let provider = state.db.get_universal_provider(id)?;
+
+        // 删除统一供应商
+        state.db.delete_universal_provider(id)?;
+
+        // 删除生成的子供应商
+        if let Some(p) = provider {
+            if p.apps.claude {
+                let claude_id = format!("universal-claude-{}", id);
+                let _ = state.db.delete_provider("claude", &claude_id);
+            }
+            if p.apps.codex {
+                let codex_id = format!("universal-codex-{}", id);
+                let _ = state.db.delete_provider("codex", &codex_id);
+            }
+            if p.apps.gemini {
+                let gemini_id = format!("universal-gemini-{}", id);
+                let _ = state.db.delete_provider("gemini", &gemini_id);
+            }
+        }
+
+        Ok(true)
+    }
+
+    /// 同步统一供应商到各应用
+    pub fn sync_universal_to_apps(state: &AppState, id: &str) -> Result<bool, AppError> {
+        let provider = state
+            .db
+            .get_universal_provider(id)?
+            .ok_or_else(|| AppError::Message(format!("统一供应商 {} 不存在", id)))?;
+
+        // 同步到 Claude
+        if let Some(mut claude_provider) = provider.to_claude_provider() {
+            // 合并已有配置
+            if let Some(existing) = state.db.get_provider_by_id(&claude_provider.id, "claude")? {
+                let mut merged = existing.settings_config.clone();
+                Self::merge_json(&mut merged, &claude_provider.settings_config);
+                claude_provider.settings_config = merged;
+            }
+            state.db.save_provider("claude", &claude_provider)?;
+        } else {
+            // 如果禁用了 Claude，删除对应的子供应商
+            let claude_id = format!("universal-claude-{}", id);
+            let _ = state.db.delete_provider("claude", &claude_id);
+        }
+
+        // 同步到 Codex
+        if let Some(mut codex_provider) = provider.to_codex_provider() {
+            // 合并已有配置
+            if let Some(existing) = state.db.get_provider_by_id(&codex_provider.id, "codex")? {
+                let mut merged = existing.settings_config.clone();
+                Self::merge_json(&mut merged, &codex_provider.settings_config);
+                codex_provider.settings_config = merged;
+            }
+            state.db.save_provider("codex", &codex_provider)?;
+        } else {
+            let codex_id = format!("universal-codex-{}", id);
+            let _ = state.db.delete_provider("codex", &codex_id);
+        }
+
+        // 同步到 Gemini
+        if let Some(mut gemini_provider) = provider.to_gemini_provider() {
+            // 合并已有配置
+            if let Some(existing) = state.db.get_provider_by_id(&gemini_provider.id, "gemini")? {
+                let mut merged = existing.settings_config.clone();
+                Self::merge_json(&mut merged, &gemini_provider.settings_config);
+                gemini_provider.settings_config = merged;
+            }
+            state.db.save_provider("gemini", &gemini_provider)?;
+        } else {
+            let gemini_id = format!("universal-gemini-{}", id);
+            let _ = state.db.delete_provider("gemini", &gemini_id);
+        }
+
+        Ok(true)
+    }
+
+    /// 递归合并 JSON：base 为底，patch 覆盖同名字段
+    fn merge_json(base: &mut serde_json::Value, patch: &serde_json::Value) {
+        use serde_json::Value;
+
+        match (base, patch) {
+            (Value::Object(base_map), Value::Object(patch_map)) => {
+                for (k, v_patch) in patch_map {
+                    match base_map.get_mut(k) {
+                        Some(v_base) => Self::merge_json(v_base, v_patch),
+                        None => {
+                            base_map.insert(k.clone(), v_patch.clone());
+                        }
+                    }
+                }
+            }
+            // 其它类型：直接覆盖
+            (base_val, patch_val) => {
+                *base_val = patch_val.clone();
+            }
+        }
+    }
+}