fix: past days UX improvements and clear missed logic (#152)

- Render past days above 'Show past days' toggle when expanded
- Auto-scroll to today when expanding past days
- Remove blue hover color from past day dividers (use opacity instead)
- Fix 'All taken' logic: green only for manually taken doses
- Yellow styling stays for days with non-taken doses (even after dismissal)
- Warning icon disappears after 'Clear missed' (dismissed doses not counted)

frontend/src/styles.css

@@ -1500,7 +1500,7 @@ textarea.auto-resize {
 	user-select: none;
 }
 .day-divider.clickable:hover {
-	color: var(--accent);
+	opacity: 0.8;
 }
 /* Keep warning/danger colors on hover */
 .day-block.stock-warning .day-divider.clickable:hover {