feat(web): Modal overlay gets p-4 so max-w-md modals fit on phone

Without padding, max-w-md (448px) modals touch the viewport edges
on a 375px screen. p-4 on the overlay clamps them inside the safe
area. Covers all routes that use the shared <Modal> component
(discover track-confirm, quarantine typed-DELETE, users
password-reset, etc.).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

web/src/lib/components/Modal.svelte

@@ -39,7 +39,7 @@
 <svelte:window onkeydown={onKeyDown} />
 
 {#if open}
-  <div class="fixed inset-0 z-50 flex items-center justify-center" role="presentation">
+  <div class="fixed inset-0 z-50 flex items-center justify-center p-4" role="presentation">
     <!-- svelte-ignore a11y_click_events_have_key_events -->
     <!-- svelte-ignore a11y_no_static_element_interactions -->
     <!-- Backdrop click closes modal; ESC handled at window level above. -->