fix(pres_mgmt): use w-full on Session and Presenter page sections

Session ID page: replace `container mx-auto` with `w-full` — removes the
Tailwind breakpoint max-width cap that was narrower than the outer layout's
max-w-7xl on smaller desktop viewports, and eliminates the double-padding
from nested container classes.

Presenter ID page: replace the conflicting `md:container items-center mx-auto
h-full min-w-full max-w-max` with a clean `w-full`. The `items-center` was
the main bug — in flex-col context it horizontally centered children (presenter
details, file upload form, file list) at their content width instead of
stretching them to fill the available space. Removes all of the conflicting
min/max width overrides.

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

src/routes/events/[event_id]/(pres_mgmt)/presenter/[presenter_id]/+page.svelte

@@ -124,20 +124,7 @@
     </title>
 </svelte:head>
 
-<section
-    class="
-        ae_events_pres_mgmt_event_presenter
-        md:container
-        flex flex-col gap-1
-        items-center
-        justify-start
-        mx-auto
-        py-1 px-2 pb-16
-        h-full
-        min-w-full
-        max-w-max
-        "
->
+<section class="ae_events_pres_mgmt_event_presenter w-full flex flex-col gap-1 py-1 px-2 pb-16">
     <Presenter_page_menu {lq__event_obj} {lq__event_presenter_obj} />
 
     {#if !$lq__event_presenter_obj}

src/routes/events/[event_id]/(pres_mgmt)/session/[session_id]/+page.svelte

@@ -99,7 +99,7 @@
     </title>
 </svelte:head>
 
-<section class="ae_events_pres_mgmt_event_session container mx-auto py-1 px-2 pb-16 space-y-6">
+<section class="ae_events_pres_mgmt_event_session w-full py-1 px-2 pb-16 space-y-6">
 
     <!-- Pass observable STORES to child components (they use $) -->
     <Session_page_menu {data} {lq__event_session_obj} {lq__auth__event_presenter_obj} />