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/services/provider/mod.rs

@@ -380,6 +380,7 @@ impl ProviderService {
             AppType::Claude => Self::extract_claude_common_config(&provider.settings_config),
             AppType::Codex => Self::extract_codex_common_config(&provider.settings_config),
             AppType::Gemini => Self::extract_gemini_common_config(&provider.settings_config),
+            AppType::OpenCode => Self::extract_opencode_common_config(&provider.settings_config),
         }
     }
 
@@ -392,6 +393,7 @@ impl ProviderService {
             AppType::Claude => Self::extract_claude_common_config(settings_config),
             AppType::Codex => Self::extract_codex_common_config(settings_config),
             AppType::Gemini => Self::extract_gemini_common_config(settings_config),
+            AppType::OpenCode => Self::extract_opencode_common_config(settings_config),
         }
     }
 
@@ -525,6 +527,29 @@ impl ProviderService {
             .map_err(|e| AppError::Message(format!("Serialization failed: {e}")))
     }
 
+    /// Extract common config for OpenCode (JSON format)
+    fn extract_opencode_common_config(settings: &Value) -> Result<String, AppError> {
+        // OpenCode uses a different config structure with npm, options, models
+        // For common config, we exclude provider-specific fields like apiKey
+        let mut config = settings.clone();
+
+        // Remove provider-specific fields
+        if let Some(obj) = config.as_object_mut() {
+            if let Some(options) = obj.get_mut("options").and_then(|v| v.as_object_mut()) {
+                options.remove("apiKey");
+                options.remove("baseURL");
+            }
+            // Keep npm and models as they might be common
+        }
+
+        if config.is_null() || (config.is_object() && config.as_object().unwrap().is_empty()) {
+            return Ok("{}".to_string());
+        }
+
+        serde_json::to_string_pretty(&config)
+            .map_err(|e| AppError::Message(format!("Serialization failed: {e}")))
+    }
+
     /// Import default configuration from live files (re-export)
     ///
     /// Returns `Ok(true)` if imported, `Ok(false)` if skipped.
@@ -691,6 +716,17 @@ impl ProviderService {
                 use crate::gemini_config::validate_gemini_settings;
                 validate_gemini_settings(&provider.settings_config)?
             }
+            AppType::OpenCode => {
+                // OpenCode uses a different config structure: { npm, options, models }
+                // Basic validation - must be an object
+                if !provider.settings_config.is_object() {
+                    return Err(AppError::localized(
+                        "provider.opencode.settings.not_object",
+                        "OpenCode 配置必须是 JSON 对象",
+                        "OpenCode configuration must be a JSON object",
+                    ));
+                }
+            }
         }
 
         // Validate and clean UsageScript configuration (common for all app types)
@@ -828,6 +864,40 @@ impl ProviderService {
 
                 Ok((api_key, base_url))
             }
+            AppType::OpenCode => {
+                // OpenCode uses options.apiKey and options.baseURL
+                let options = provider
+                    .settings_config
+                    .get("options")
+                    .and_then(|v| v.as_object())
+                    .ok_or_else(|| {
+                        AppError::localized(
+                            "provider.opencode.options.missing",
+                            "配置格式错误: 缺少 options",
+                            "Invalid configuration: missing options section",
+                        )
+                    })?;
+
+                let api_key = options
+                    .get("apiKey")
+                    .and_then(|v| v.as_str())
+                    .ok_or_else(|| {
+                        AppError::localized(
+                            "provider.opencode.api_key.missing",
+                            "缺少 API Key",
+                            "API key is missing",
+                        )
+                    })?
+                    .to_string();
+
+                let base_url = options
+                    .get("baseURL")
+                    .and_then(|v| v.as_str())
+                    .unwrap_or("")
+                    .to_string();
+
+                Ok((api_key, base_url))
+            }
         }
     }
 }