refactor: complete Svelte 5 migration to eliminate all deprecation warnings

Migrated all components and routes to Svelte 5 syntax standards:

Event Handlers:
- Updated all deprecated on:* directives to new on* attribute syntax
- Changed on:click → onclick, on:keydown → onkeydown, on:input → oninput
- Updated on:blur, on:focus, on:load, on:submit, on:cancel handlers

Reactive State:
- Added $state() declarations for all reactive variables
- Fixed non-reactive update warnings in layout and component files

Component API:
- Replaced <slot /> with {@render children()} pattern
- Added children prop to components using slots

Accessibility:
- Added id attributes to inputs and for attributes to labels
- Fixed label-control associations across forms
- Removed event listeners from non-interactive elements

HTML Fixes:
- Fixed self-closing textarea tags
- Corrected implicitly closed elements
- Proper element nesting

CSS Cleanup:
- Removed 20+ unused CSS selectors across components
- Cleaned up orphaned styles from refactoring

All vite-plugin-svelte warnings resolved. Codebase now fully compliant with Svelte 5.

src/lib/components/TitleImgParallax.svelte

@@ -1,7 +1,7 @@
 <script>
 	import { onMount } from "svelte";
 
-	let { src, placeholder_src, alt = "" } = $props();
+	let { src, placeholder_src, alt = "", children } = $props();
 
 	let isloaded = $state(false);
 	let isredirected = $state(false);
@@ -189,7 +189,7 @@ dialog button{
 		</noscript>
 	</div>
     </figure>
-    <div class=content><slot></slot></div>
+    <div class=content>{@render children()}</div>
 </section>
 
 <dialog id=img_carousel>