fix mobile responsiveness issues

- Fixed malformed .mobile-nav-btn CSS syntax
- Added global overflow-x: hidden to prevent horizontal scroll
- Made projects.js use consistent sidebar overlay approach
- Removed hardcoded min-width: 450px from all modals
- Added safe area insets for notched mobile devices
- Hamburger menu now appears on ALL views on mobile
- Sidebar slides in as overlay on mobile
- All touch targets are at least 44px
- Font sizes are at least 16px to prevent iOS zoom
- Modals are full-width on mobile

public/css/style.css

@@ -109,6 +109,7 @@
 html {
   font-size: 16px;
   -webkit-font-smoothing: antialiased;
+  overflow-x: hidden;
 }
 
 body {
@@ -118,6 +119,7 @@ body {
   color: var(--color-text);
   background: var(--color-bg);
   min-height: 100vh;
+  overflow-x: hidden;
 }
 
 a {
@@ -1240,7 +1242,7 @@ ul, ol {
 }
 
 /* === Mobile Navigation Drawer === */
-.mobile-nav-btn { display: flex; margin-right: 8px; } .mobile-nav-btnOLD {
+.mobile-nav-btn {
   display: none;
   width: 44px;
   height: 44px;
@@ -1248,9 +1250,24 @@ ul, ol {
   justify-content: center;
   border-radius: var(--radius-md);
   color: var(--color-text-secondary);
-  font-size: 1.25rem;
+  font-size: 1.5rem;
   transition: var(--transition-fast);
   flex-shrink: 0;
+  cursor: pointer;
+  background: transparent;
+  border: none;
+  padding: 0;
+}
+
+.mobile-nav-btn:hover {
+  background: var(--color-hover);
+  color: var(--color-text);
+}
+
+@media (max-width: 1024px) {
+  .mobile-nav-btn {
+    display: flex;
+  }
 }
 
 .mobile-nav-btn:hover {
@@ -2019,3 +2036,23 @@ ul, ol {
     display: block;
   }
 }
+
+/* Safe area insets for notched devices */
+@supports (padding: env(safe-area-inset-top)) {
+  body {
+    padding-top: env(safe-area-inset-top);
+    padding-bottom: env(safe-area-inset-bottom);
+    padding-left: env(safe-area-inset-left);
+    padding-right: env(safe-area-inset-right);
+  }
+  
+  .app-header {
+    padding-top: calc(var(--space-3) + env(safe-area-inset-top));
+  }
+  
+  #toast-container {
+    bottom: calc(var(--space-6) + env(safe-area-inset-bottom));
+    right: calc(var(--space-6) + env(safe-area-inset-right));
+    left: calc(var(--space-6) + env(safe-area-inset-left));
+  }
+}