feat: finish all UI/UX improvements from backlog

- nav: aria-label on baby switcher select
- dashboard: active timers show baby name
- growth: PDF export includes percentile band per weight row
- settings: invite link note (permanent, reset if compromised)
- timeline: select mode toggle shows "Annuler" when active
- photos: delete photo from lightbox (PATCHes event metadata)
- notes: invisible date input overlay for date-jump via calendar picker
- IMPROVEMENTS.md: updated checkboxes, 8 remaining → 0

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

src/app/(app)/timeline/page.tsx

@@ -156,7 +156,7 @@ export default function TimelinePage() {
             }`}
           >
             <CheckSquare className="w-3.5 h-3.5" />
-            Sélectionner
+            {selectMode ? "Annuler" : "Sélectionner"}
           </button>
         </div>
         {/* Filter chips */}