Enhance smoking tracking features with AI next smoke time suggestions

- Added new API endpoint `GET /api/v1/smoke/next_smoke_time` to provide AI-generated suggestions for the next smoking time based on user data.
- Introduced a new database table `fa_smoke_ai_next_smoke` to store structured AI time node suggestions.
- Updated smoke handler and service to integrate the new AI next smoke time functionality.
- Enhanced documentation to reflect the new API endpoint and its usage, including details on how to generate AI time nodes.

internal/smoke/handler/smoke_ai_next_smoke_handler.go

@@ -0,0 +1,12 @@
+package handler
+
+import (
+	"github.com/gin-gonic/gin"
+)
+
+func (h *SmokeHandler) GetAINextSmokeTime(c *gin.Context) {
+	q := c.Request.URL.Query()
+	q.Set("mode", "ai")
+	c.Request.URL.RawQuery = q.Encode()
+	h.GetNextSmokeTime(c)
+}