Fix mobile pinch zoom and content overlapping header/footer on iOS Safari (#3)

* Fix mobile pinch zoom and content overlapping header/footer on iOS Safari

Add viewport export with maximumScale=1 and userScalable=false to prevent
pinch-to-zoom. Add viewportFit=cover for proper safe area support.

Fix content rendering above the sticky header and below the fixed mobile
tab bar on iOS Safari by adding relative z-0 to the content wrapper,
creating a stacking context that keeps page content below both navigation
elements.

https://claude.ai/code/session_01Re8ndXPAMVMtiHZFVNDK7S

* Add safe area inset support for iOS 26 and fix film grain z-index

- Add safe-area-inset-top padding to NavBar for notch/Dynamic Island
- Add safe-area-inset-left/right to NavBar, main content, and
  MobileTabBar for landscape mode
- Account for safe-area-inset-bottom in content wrapper padding so
  content isn't hidden behind MobileTabBar + home indicator
- Lower film grain overlay z-index from 9999 to 1 to avoid triggering
  iOS 26 Safari's fixed-element tab tinting behavior

https://claude.ai/code/session_01Re8ndXPAMVMtiHZFVNDK7S

* Hide ambient glow on mobile where it overwhelms the viewport

The 800x600px blurred glow blob dominates narrow mobile screens and
clashes with title backdrop images. Hidden below sm breakpoint.

https://claude.ai/code/session_01Re8ndXPAMVMtiHZFVNDK7S

* Fix asymmetric safe-area insets using separate pl/pr padding

The previous px-[max(...,env(safe-area-inset-left))] shorthand applied
only the left inset to both sides. Split into separate pl/pr with the
correct env() variable for each side.

https://claude.ai/code/session_01Re8ndXPAMVMtiHZFVNDK7S

---------

Co-authored-by: Claude <noreply@anthropic.com>

app/globals.css

@@ -102,7 +102,7 @@
     content: "";
     position: fixed;
     inset: 0;
-    z-index: 9999;
+    z-index: 1;
     pointer-events: none;
     opacity: 0.015;
     background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)'/%3E%3C/svg%3E");