fix(pres_mgmt): make POC list/table column a real per-event config

show__session_li_poc_field was local-browser-only and the session list
prop computation ignored the admin's hide__session_poc master switch
entirely, so disabling POC for an event didn't hide the column if a
user's browser had it toggled on.

- Add show__session_li_poc_field to PressMgmtRemoteCfg + Config page UI
  (Session Field Visibility) + sync_config__event_pres_mgmt() lock-synced
  block, so it's admin-configurable per event like the other display flags
- Fix list/table column visibility to hide__session_poc || !show__session_li_poc_field
  in pres_mgmt/+page.svelte and locations/ae_comp__event_location_obj_li.svelte
- Remove the now-redundant local "Show/Hide POC Column" toggle buttons from
  ae_comp__events_menu_opts.svelte and event_page_menu.svelte
- Log the fix in PROJECT__AE_Events_PressMgmt_Config_Cleanup.md

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

src/routes/events/ae_comp__events_menu_opts.svelte

@@ -540,27 +540,9 @@ import {
                     </span>
                 </button>
 
-                <!-- Show/Hide the POC column in tables and lists -->
-                <button
-                    type="button"
-                    onclick={() => {
-                        pres_mgmt_loc.current.show__session_li_poc_field =
-                            !pres_mgmt_loc.current.show__session_li_poc_field;
-                    }}
-                    class="btn btn-sm ae_btn_surface w-full justify-between text-center"
-                    title="Toggle showing the POC column in session lists and tables">
-                    {#if !pres_mgmt_loc.current.show__session_li_poc_field}<ToggleLeft
-                            size="1em"
-                            class="m-1" />{:else}<ToggleRight
-                            size="1em"
-                            class="m-1" />{/if}
-                    <span class="grow">
-                        <!-- <span class="fas fa-user-tie m-1"></span> -->
-                        {!pres_mgmt_loc.current.show__session_li_poc_field
-                            ? 'Show POC Column'
-                            : 'Hide POC Column?'}
-                    </span>
-                </button>
+                <!-- POC column visibility is a per-event config (Config page), not a
+                     local toggle — removed 2026-06-16, see
+                     PROJECT__AE_Events_PressMgmt_Config_Cleanup.md -->
 
                 <!-- These are related to more content showing in lists. -->
                 <span