Move tougher analytical questions higher in the list

- Move the 4 harder questions to positions 11-14 so they're visible in the first 15
- Questions now visible:
* Which station records highest variability in PM2.5?
* Calculate pollution improvement rate year-over-year by city
* Identify cities with PM2.5 levels consistently above 50 μg/m³ for >6 months
* Find correlation between PM2.5 and PM10 across different seasons and cities
- These should now appear in the sidebar instead of being cut off

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

app.py

@@ -599,14 +599,14 @@ with st.sidebar:
             "Which areas exceed WHO guidelines?",
             "What are peak pollution hours?",
             "Show PM10 vs PM2.5 comparison",
-            "Compare weekday vs weekend levels",
-            "Plot yearly trend analysis",
-            "Show pollution distribution by city",
-            "Create correlation plot between pollutants",
             "Which station records highest variability in PM2.5?",
             "Calculate pollution improvement rate year-over-year by city",
             "Identify cities with PM2.5 levels consistently above 50 μg/m³ for >6 months",
-            "Find correlation between PM2.5 and PM10 across different seasons and cities"
+            "Find correlation between PM2.5 and PM10 across different seasons and cities",
+            "Compare weekday vs weekend levels",
+            "Plot yearly trend analysis",
+            "Show pollution distribution by city",
+            "Create correlation plot between pollutants"
         ]
     
     # Quick query buttons in sidebar