Improve Mobile UI for dialogs and action dropdowns (#16222)

* fix: Always show conversation item actions

* feat: Improve Alert Dialog and Dialog mobile UI

* feat: Add settings reset to default confirmation

* fix: Close Edit dialog on save

* chore: update webui build output

* webui: implement proper z-index system and scroll management

- Add CSS variable for centralized z-index control
- Fix dropdown positioning with Settings dialog conflicts
- Prevent external scroll interference with proper event handling
- Clean up hardcoded z-index values for maintainable architecture

* webui: ensured the settings dialog enforces dynamic viewport height on mobile while retaining existing desktop sizing overrides

* feat: Use `dvh` instead of computed px height for dialogs max height on mobile

* chore: update webui build output

* feat: Improve Settings fields UI

* chore: update webui build output

* chore: update webui build output

---------

Co-authored-by: Pascal <admin@serveurperso.com>

tools/server/webui/src/lib/components/ui/dialog/dialog-content.svelte

@@ -25,7 +25,7 @@
 		bind:ref
 		data-slot="dialog-content"
 		class={cn(
-			'fixed top-[50%] left-[50%] z-50 grid w-full max-w-[calc(100%-2rem)] translate-x-[-50%] translate-y-[-50%] gap-4 rounded-lg border border-border/30 bg-background p-6 shadow-lg duration-200 data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=closed]:zoom-out-95 data-[state=open]:animate-in data-[state=open]:fade-in-0 data-[state=open]:zoom-in-95 sm:max-w-lg',
+			`fixed top-[50%] left-[50%] z-50 grid max-h-[100dvh] w-full max-w-[calc(100%-2rem)] translate-x-[-50%] translate-y-[-50%] gap-4 overflow-y-auto rounded-lg border border-border/30 bg-background p-6 shadow-lg duration-200 data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=closed]:zoom-out-95 data-[state=open]:animate-in data-[state=open]:fade-in-0 data-[state=open]:zoom-in-95 sm:max-w-lg md:max-h-[100vh]`,
 			className
 		)}
 		{...restProps}