fix(icons): replace hand-rolled inline SVGs with Lucide (header, search)

Header: same magnifying-glass path was hand-duplicated twice with two
different hex fills (#576463 desktop, #1e3c38 mobile) - now one
app-icon name="search", color inherited via currentColor. Wishlist/
compare buttons used bare '♥'/'⇄' text glyphs, entirely outside any
icon system - replaced with heart/scale icons. Cart icon, mobile-menu
home/catalog icons, and three duplicated inline chevron SVGs replaced
with app-icon equivalents. Cleaned up now-dead CSS that targeted the
old raw svg/path selectors.

Search: the same magnifying-glass path was hand-duplicated 4 times
(input icon, empty-query state, no-results state, no-query state) at
three sizes and three colors. Replaced all four with app-icon,
preserving each state's intended color via a color property on the
wrapper (icons default to currentColor).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/app/components/header/header.component.scss

@@ -299,20 +299,10 @@
     background: #497671;
     color: #ffffff;
     border-color: #497671;
-
-    svg path {
-      fill: #ffffff;
-    }
-
-    .platform-mobile-chevron path {
-      stroke: #ffffff;
-    }
   }
 
-  svg:first-child {
+  app-icon:first-child {
     flex-shrink: 0;
-    width: 24px;
-    height: 24px;
   }
 
   span {