feat(opencode): Phase 1 - Backend data structure expansion for OpenCode support

Add OpenCode as the 4th supported application with additive provider management:

- Add OpenCode variant to AppType enum with all related match statements
- Add enabled_opencode field to McpApps and SkillApps structures
- Add opencode field to McpRoot and PromptRoot
- Add database schema migration v3→v4 with enabled_opencode columns
- Add settings.rs support for opencode_config_dir and current_provider_opencode
- Create opencode_config.rs module for config file I/O operations
- Update all services (proxy, mcp, skill, provider, stream_check) for OpenCode
- Add OpenCode support to deeplink provider and MCP parsing
- Update commands/config.rs for OpenCode config status and paths

Key design decisions:
- OpenCode uses additive mode (no is_current needed, no proxy support)
- Config path: ~/.config/opencode/opencode.json
- MCP format: stdio→local, sse/http→remote conversion planned
- Stream check returns error (not yet implemented for OpenCode)

src-tauri/src/database/schema.rs

@@ -58,7 +58,7 @@ impl Database {
             id TEXT PRIMARY KEY, name TEXT NOT NULL, server_config TEXT NOT NULL,
             description TEXT, homepage TEXT, docs TEXT, tags TEXT NOT NULL DEFAULT '[]',
             enabled_claude BOOLEAN NOT NULL DEFAULT 0, enabled_codex BOOLEAN NOT NULL DEFAULT 0,
-            enabled_gemini BOOLEAN NOT NULL DEFAULT 0
+            enabled_gemini BOOLEAN NOT NULL DEFAULT 0, enabled_opencode BOOLEAN NOT NULL DEFAULT 0
         )",
             [],
         )
@@ -85,6 +85,7 @@ impl Database {
             enabled_claude BOOLEAN NOT NULL DEFAULT 0,
             enabled_codex BOOLEAN NOT NULL DEFAULT 0,
             enabled_gemini BOOLEAN NOT NULL DEFAULT 0,
+            enabled_opencode BOOLEAN NOT NULL DEFAULT 0,
             installed_at INTEGER NOT NULL DEFAULT 0
         )",
             [],
@@ -346,6 +347,11 @@ impl Database {
                         Self::migrate_v2_to_v3(conn)?;
                         Self::set_user_version(conn, 3)?;
                     }
+                    3 => {
+                        log::info!("迁移数据库从 v3 到 v4（OpenCode 支持）");
+                        Self::migrate_v3_to_v4(conn)?;
+                        Self::set_user_version(conn, 4)?;
+                    }
                     _ => {
                         return Err(AppError::Database(format!(
                             "未知的数据库版本 {version}，无法迁移到 {SCHEMA_VERSION}"
@@ -849,6 +855,30 @@ impl Database {
         Ok(())
     }
 
+    /// v3 -> v4 迁移：添加 OpenCode 支持
+    ///
+    /// 为 mcp_servers 和 skills 表添加 enabled_opencode 列。
+    fn migrate_v3_to_v4(conn: &Connection) -> Result<(), AppError> {
+        // 为 mcp_servers 表添加 enabled_opencode 列
+        Self::add_column_if_missing(
+            conn,
+            "mcp_servers",
+            "enabled_opencode",
+            "BOOLEAN NOT NULL DEFAULT 0",
+        )?;
+
+        // 为 skills 表添加 enabled_opencode 列
+        Self::add_column_if_missing(
+            conn,
+            "skills",
+            "enabled_opencode",
+            "BOOLEAN NOT NULL DEFAULT 0",
+        )?;
+
+        log::info!("v3 -> v4 迁移完成：已添加 OpenCode 支持");
+        Ok(())
+    }
+
     /// 插入默认模型定价数据
     /// 格式: (model_id, display_name, input, output, cache_read, cache_creation)
     /// 注意: model_id 使用短横线格式（如 claude-haiku-4-5），与 API 返回的模型名称标准化后一致