feat(settings): refactor agent auth modes and add model provider authentication

- Split env vars and config file persistence into separate save operations
- Add model_provider_id field to agent_setting for tracking selected provider
- Add "Model Provider" auth mode for Claude Code, Codex CLI, and Gemini CLI
- Add "Custom Endpoint" auth mode for Claude Code (previously only official subscription)
- Unify auth mode labels across all three agents (official subscription / custom endpoint / model provider)
- When model provider is selected, fill api_url and api_key into env and config automatically
- Resolve model provider credentials at ACP connect time as a backend fallback
- Clear provider deletion cascades to agent_setting.model_provider_id
- Claude Code writes API credentials to config.env (ANTHROPIC_BASE_URL / ANTHROPIC_AUTH_TOKEN)
- Codex: switching auth modes patches config.toml instead of clearing it
- Add i18n keys for new auth modes in all 10 supported languages

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src-tauri/src/db/entities/agent_setting.rs

@@ -11,6 +11,7 @@ pub struct Model {
     pub sort_order: i32,
     pub installed_version: Option<String>,
     pub env_json: Option<String>,
+    pub model_provider_id: Option<i32>,
     pub created_at: DateTimeUtc,
     pub updated_at: DateTimeUtc,
 }

src-tauri/src/db/migration/m20260406_000001_agent_setting_model_provider.rs

@@ -0,0 +1,35 @@
+use sea_orm_migration::prelude::*;
+
+#[derive(DeriveMigrationName)]
+pub struct Migration;
+
+#[async_trait::async_trait]
+impl MigrationTrait for Migration {
+    async fn up(&self, manager: &SchemaManager) -> Result<(), DbErr> {
+        manager
+            .alter_table(
+                Table::alter()
+                    .table(AgentSetting::Table)
+                    .add_column(ColumnDef::new(AgentSetting::ModelProviderId).integer().null())
+                    .to_owned(),
+            )
+            .await
+    }
+
+    async fn down(&self, manager: &SchemaManager) -> Result<(), DbErr> {
+        manager
+            .alter_table(
+                Table::alter()
+                    .table(AgentSetting::Table)
+                    .drop_column(AgentSetting::ModelProviderId)
+                    .to_owned(),
+            )
+            .await
+    }
+}
+
+#[derive(DeriveIden)]
+enum AgentSetting {
+    Table,
+    ModelProviderId,
+}

src-tauri/src/db/migration/mod.rs

@@ -8,6 +8,7 @@ mod m20260227_000001_folder_parent_branch;
 mod m20260330_000001_chat_channel;
 mod m20260401_000001_chat_channel_sender_context;
 mod m20260404_000001_model_provider;
+mod m20260406_000001_agent_setting_model_provider;
 pub struct Migrator;
 
 #[async_trait::async_trait]
@@ -22,6 +23,7 @@ impl MigratorTrait for Migrator {
             Box::new(m20260330_000001_chat_channel::Migration),
             Box::new(m20260401_000001_chat_channel_sender_context::Migration),
             Box::new(m20260404_000001_model_provider::Migration),
+            Box::new(m20260406_000001_agent_setting_model_provider::Migration),
         ]
     }
 }

src-tauri/src/db/service/agent_setting_service.rs

@@ -22,6 +22,7 @@ pub struct AgentDefaultInput {
 pub struct AgentSettingsUpdate {
     pub enabled: bool,
     pub env_json: Option<String>,
+    pub model_provider_id: Option<i32>,
 }
 
 fn default_enabled(agent_type: AgentType) -> bool {
@@ -67,6 +68,7 @@ pub async fn ensure_defaults(
             sort_order: Set(default.default_sort_order),
             installed_version: Set(None),
             env_json: Set(None),
+            model_provider_id: Set(None),
             created_at: Set(now),
             updated_at: Set(now),
         };
@@ -133,6 +135,7 @@ pub async fn update(
     let mut active = model.into_active_model();
     active.enabled = Set(patch.enabled);
     active.env_json = Set(patch.env_json);
+    active.model_provider_id = Set(patch.model_provider_id);
     active.updated_at = Set(Utc::now());
     active.update(conn).await?;
     Ok(())
@@ -202,6 +205,25 @@ async fn reorder_once(conn: &DatabaseConnection, agent_types: &[AgentType]) -> R
     Ok(())
 }
 
+pub async fn clear_model_provider_id(
+    conn: &DatabaseConnection,
+    model_provider_id: i32,
+) -> Result<(), DbError> {
+    let rows = agent_setting::Entity::find()
+        .all(conn)
+        .await?;
+    let now = Utc::now();
+    for row in rows {
+        if row.model_provider_id == Some(model_provider_id) {
+            let mut active = row.into_active_model();
+            active.model_provider_id = Set(None);
+            active.updated_at = Set(now);
+            active.update(conn).await?;
+        }
+    }
+    Ok(())
+}
+
 fn is_sqlite_full_error(err: &DbError) -> bool {
     let message = err.to_string();
     message.contains("database or disk is full") || message.contains("(code: 13)")