feat(events): restore inc_file_counts opt-in, session list layout + button polish

- Add `inc_file_counts` flag to `load_ae_obj_id__event_session` — maps to
  backend alt view (v_event_session_w_file_count) when true; default stays
  lightweight. Callers never pass raw view names.
- Preserve-on-write fallback in `_refresh_session_id_background` keeps
  cached file_count/file_count_all if API response omits them.
- Session detail +page.ts uses `inc_file_counts: true` so SvelteKit prefetch
  no longer clobbers counts via bulkPut on hover.
- Remove explicit `view: 'alt'` from launcher +page.ts (now invalid param).
- Session list link: flex-1 + min-w-0 for full-row width; name flex-1 pushes
  badge group right; code + file_count stacked in flex-col items-end.
- Hover styling: button-like appearance with slow fade-out (duration-500) /
  fast snap-in (hover:duration-150).
- Session +page.svelte: use url_session_id (string) for link_to_id props and
  auth__kv.session[] index — fixes TS type error from number|undefined.
- IDAA layout: dormant tech notice banner (guarded by 1==3, remove when ready).

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

src/routes/idaa/(idaa)/+layout.svelte

@@ -64,6 +64,17 @@ let verify_failed_for_uuid: string | null = null;
 // Handles the case where site_cfg_json loads without novi_idaa_api_key (stale cache)
 // or the Novi API call hangs — the user would otherwise be stuck with no escape.
 const VERIFY_TIMEOUT_MS = 8000;
+
+// One-time technical notice banner — persisted in localStorage so it only shows once.
+// TEMPORARY (2026-04-01): Remove this block after a few days.
+const TECH_NOTICE_KEY = 'idaa_tech_notice_2026_04_01_dismissed';
+let show_tech_notice: boolean = $state(
+    browser ? localStorage.getItem(TECH_NOTICE_KEY) !== 'true' : false
+);
+function dismiss_tech_notice() {
+    show_tech_notice = false;
+    try { localStorage.setItem(TECH_NOTICE_KEY, 'true'); } catch { /* storage unavailable */ }
+}
 let verifying_timed_out: boolean = $state(false);
 
 $effect(() => {
@@ -353,6 +364,28 @@ async function verify_novi_uuid(
         {/if}
     </div>
 {:else if $ae_loc.trusted_access || ($ae_loc.authenticated_access && $idaa_loc.novi_uuid && $idaa_loc.novi_verified)}
+    {#if show_tech_notice && 1 == 3}
+        <!-- TEMPORARY (2026-04-01): One-time notice about last night's technical issues. Remove after a few days. -->
+        <div class="m-2 flex items-start gap-3 rounded-lg border border-yellow-400 bg-yellow-50 p-3 text-yellow-900 dark:border-yellow-600 dark:bg-yellow-950 dark:text-yellow-100">
+            <span class="fas fa-exclamation-triangle mt-0.5 shrink-0 text-yellow-500"></span>
+            <p class="flex-1 text-sm">
+                Opt 1:
+                <strong>Notice:</strong> We experienced technical difficulties last night (March 31) and this morning (April 1). Things are back to normal. We apologize for any inconvenience.
+
+                <br>
+                <br>
+
+                Opt 2:
+                <strong>Notice:</strong> We have experienced some technical difficulties recently. Things are back to normal. We apologize for any inconvenience.
+            </p>
+            <button
+                type="button"
+                class="shrink-0 rounded px-2 py-1 text-xs font-semibold hover:bg-yellow-200 dark:hover:bg-yellow-800 btn"
+                onclick={dismiss_tech_notice}>
+                OK
+            </button>
+        </div>
+    {/if}
     {@render children?.()}
     {#if $idaa_loc.novi_uuid}
         <span class="text-sm text-gray-500">