fix(pwa): fix remaining iOS scroll bleed and safe-area height overflow (#16)

Root cause 1 (scroll bleed): padding-top was applied to body in standalone
mode. Since .app-shell has height: 100dvh, body-padding shifted the shell
beyond the viewport bottom - enabling body-level scrolling.
Fix: moved padding-top from body to .app-shell in the standalone media query.

Root cause 2 (content overflow): fixed-height page containers
(Calendar, Shopping, Meals, Notes, Budget, Contacts) calculated height as
100dvh - nav-bottom - safe-area-inset-bottom, but never subtracted the top
safe area. This caused each page to overflow .app-content by exactly
env(safe-area-inset-top) pixels in standalone mode.
Fix: added --safe-area-inset-top token and subtracted it in all 6 height
calculations.

Service worker cache bumped to v27/v26.

public/styles/pwa.css

@@ -16,9 +16,11 @@ html, body {
 }
 
 /* ── Safe Area Insets (Notch, Dynamic Island, Gesture Bar) ──
- * Nur horizontale Safe Areas auf body - vertikale werden von
- * Standalone-Modus (padding-top) und Nav/Seiten (padding-bottom) gehandhabt.
- * Kein body padding-top/bottom hier, sonst doppelt mit Seiten-Berechnungen. */
+ * Nur horizontale Safe Areas auf body. Vertikale Safe Areas werden über
+ * .app-shell (padding-top im Standalone-Modus) und die Seiten-/Nav-Berechnungen
+ * (padding-bottom via --safe-area-inset-bottom) gehandhabt.
+ * KEIN body padding-top/bottom - das würde .app-shell (height: 100dvh)
+ * um den Safe-Area-Betrag aus dem Viewport schieben und Scroll-Bleed erzeugen. */
 body {
   padding-left: env(safe-area-inset-left);
   padding-right: env(safe-area-inset-right);
@@ -59,7 +61,10 @@ nav,
 
 /* ── Standalone-Modus: Status-Bar-Bereich berücksichtigen ── */
 @media (display-mode: standalone) {
-  body {
+  /* padding-top auf .app-shell (nicht body): So bleibt app-shell exakt 100dvh
+   * hoch und überläuft den Viewport nicht - body-padding hätte .app-shell
+   * nach unten verschoben und Scroll-Bleed verursacht. */
+  .app-shell {
     padding-top: env(safe-area-inset-top);
   }