fix(desktop): DeerFlow UI — ChatArea refactor + ai-elements + dead CSS cleanup

ChatArea retry button uses setInput instead of direct sendToGateway,
fix bootstrap spinner stuck for non-logged-in users,
remove dead CSS (aurora-title/sidebar-open/quick-action-chips),
add ai components (ReasoningBlock/StreamingText/ChatMode/ModelSelector/TaskProgress),
add ClassroomPlayer + ResizableChatLayout + artifact panel

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

crates/zclaw-saas/migrations/20260401000003_models_is_embedding.sql

@@ -0,0 +1,10 @@
+-- Add is_embedding column to models table
+-- Distinguishes embedding models from chat/completion models
+ALTER TABLE models ADD COLUMN IF NOT EXISTS is_embedding BOOLEAN NOT NULL DEFAULT FALSE;
+
+-- Add model_type column for future extensibility (chat, embedding, image, audio, etc.)
+ALTER TABLE models ADD COLUMN IF NOT EXISTS model_type TEXT NOT NULL DEFAULT 'chat';
+
+-- Index for quick filtering of embedding models
+CREATE INDEX IF NOT EXISTS idx_models_is_embedding ON models(is_embedding) WHERE is_embedding = TRUE;
+CREATE INDEX IF NOT EXISTS idx_models_model_type ON models(model_type);

crates/zclaw-saas/migrations/20260402000003_scheduled_task_results.sql

@@ -0,0 +1,5 @@
+-- Add execution result columns to scheduled_tasks
+-- Tracks the output and duration of each task execution for observability
+
+ALTER TABLE scheduled_tasks ADD COLUMN IF NOT EXISTS last_result TEXT;
+ALTER TABLE scheduled_tasks ADD COLUMN IF NOT EXISTS last_duration_ms INTEGER;