feat: service console auto-connect, settings panel, and batch of enhancements

- Auto-connect WebSocket on page load in service console
- Settings modal for editing sgclaw_config.json (API key, base URL, model, skills dir, etc.)
- UpdateConfig/ConfigUpdated protocol messages for remote config save
- save_to_path() for SgClawSettings serialization
- ConfigUpdated handler in sg_claw_client binary
- Protocol serialization tests for new message types
- HTML test assertions for auto-connect and settings UI
- Additional pending changes: deterministic submit, org units, lineloss xlsx export, browser script tool, and docs

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src/service/mod.rs

@@ -14,7 +14,7 @@ use crate::security::MacPolicy;
 const DEFAULT_BROWSER_WS_URL: &str = "ws://127.0.0.1:12345";
 const DEFAULT_SERVICE_WS_LISTEN_ADDR: &str = "127.0.0.1:42321";
 
-pub use protocol::{ClientMessage, ServiceMessage};
+pub use protocol::{ClientMessage, ConfigUpdatePayload, ServiceMessage};
 pub use server::{ServiceEventSink, ServiceSession};
 
 pub(crate) mod browser_ws_client {