fix: resolve 6 remaining defects (P2-18, P2-21, P3-04, P3-05, P3-06, P3-02)

- P2-18: TOTP QR code local generation via qrcode lib (no external service)
- P2-21: Suspend foreign LLM providers (OpenAI/Anthropic/Gemini) for early stage
- P3-04: get_progress() now calculates actual percentage from completed/total steps
- P3-05: saveSaaSSession calls now have .catch() error logging
- P3-06: SaaS relay chatStream passes session_key/agent_id to backend
- P3-02: Whiteboard unification plan document created

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

crates/zclaw-saas/src/relay/handlers.rs

@@ -200,9 +200,16 @@ pub async fn chat_completions(
     state.cache.relay_enqueue(&ctx.account_id);
 
     // 异步派发操作日志（非阻塞，不占用关键路径 DB 连接）
+    // P3-06: Include session_key/agent_id in log for traceability
+    let log_meta = serde_json::json!({
+        "model": model_name,
+        "stream": stream,
+        "session_key": req.get("session_key").and_then(|v| v.as_str()),
+        "agent_id": req.get("agent_id").and_then(|v| v.as_str()),
+    });
     state.dispatch_log_operation(
         &ctx.account_id, "relay.request", "relay_task", &task.id,
-        Some(serde_json::json!({"model": model_name, "stream": stream})), ctx.client_ip.as_deref(),
+        Some(log_meta), ctx.client_ip.as_deref(),
     ).await;
 
     // 执行中转：根据解析结果选择执行路径