style: Phase 1+2 — FA→Lucide, variant-* → preset-*, dark mode forms

Phase 1 (global quick wins):
- app.css: add global dark mode utility for .input/.select/.textarea
- events menu nav + layout: replace all FontAwesome icons with Lucide
- events settings: replace FA icons, standardize variant-* → preset-*

Phase 2 (module-by-module migration):
- root +layout.svelte: fix hardcoded banner colors → preset-filled-error/warning
- journals entry list: replace slate-* with gray-*, HSL eye colors → CSS tokens
- pres mgmt presenter view: variant-soft-warning → preset-tonal-warning, FA edit → Lucide
- badges (4 files): variant-* → preset-*, FA spinner → Lucide Loader2, dynamic alert fix
- events session list + event hub: variant-soft/filled → preset-tonal/filled
- leads module (12 files): complete variant-* → preset-* migration across all
  exhibitor sign-in, QR scanner, manual search, tracking list, manage tab,
  custom questions, license list, exhibit page, lead detail page + form

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

src/routes/events/+layout.svelte

@@ -14,7 +14,9 @@
         House,
         Library,
         RefreshCw,
-        Satellite
+        Satellite,
+        ArrowUp,
+        ArrowDown
     } from '@lucide/svelte';
 
     // *** Import Aether specific variables and functions
@@ -171,7 +173,7 @@
             }}
             title="A new version of One Sky IT's Aether Events module is available. Click to reload the page and use the latest version."
         >
-            <span class="fas fa-sync-alt fa-spin m-1"></span>
+            <RefreshCw size="1em" class="animate-spin shrink-0" aria-hidden="true" />
             <span class="m-4 sm:mx-8 text-wrap">
                 New Events Module Version Available!<br />
                 Click to Reload<br />
@@ -179,7 +181,7 @@
                     You may need to sign in again.
                 </div>
             </span>
-            <span class="fas fa-sync-alt fa-spin m-1"></span>
+            <RefreshCw size="1em" class="animate-spin shrink-0" aria-hidden="true" />
 
             <!-- <span class="text-xs">
             $events_loc.ver=${$events_loc?.ver}<br>
@@ -317,7 +319,7 @@
             }}
             title="Scroll to top"
         >
-            <span class="fas fa-arrow-up"></span>
+            <ArrowUp size="1em" aria-hidden="true" />
             Scroll to Top
         </button>
 
@@ -346,7 +348,7 @@
             }}
             title="Scroll to bottom"
         >
-            <span class="fas fa-arrow-down"></span>
+            <ArrowDown size="1em" aria-hidden="true" />
             Scroll to Bottom
             <!-- yTop={yTop} yScroll={yScroll} yHeight={yHeight} scroll_y={scroll_y} scrollTop={scroll_container().scrollTop} total={scroll_container().scrollTop + yHeight} -->
         </button>