perf(hydration): implement cache-first site discovery and SWR event loading

- Refactored lookup_site_domain_v3 to be cache-first, unblocking root layout.
- Implemented Stale-While-Revalidate (SWR) pattern for load_ae_obj_id__event.
- Added global hydration overlay and loading spinner to +layout.svelte.
- Updated site domain whitelist to persist critical account/styling metadata in Dexie.
- Refactored root load function to return immediately if cached site data is found.

src/routes/+layout.ts

@@ -123,6 +123,22 @@ export async function load({ fetch, params, parent, route, url }) {
     let api_error = false;
     let is_native = false;
 
+    // 1. FAST PATH: Check Dexie for cached site domain first
+    // This allows the load function to return nearly instantly if the user has visited before.
+    if (typeof window !== 'undefined' && (window as any).indexedDB) {
+        try {
+            // Use the db_core instance directly for a quick lookup
+            const { db_core } = await import('$lib/ae_core/db_core');
+            const cached = await db_core.site_domain.where('fqdn').equals(fqdn).first();
+            if (cached) {
+                if (log_lvl) console.log('ROOT LOAD: Found cached site domain. Unblocking layout.');
+                result = cached;
+            }
+        } catch (e) {
+            if (log_lvl) console.warn('ROOT LOAD: Failed to read from Dexie cache.', e);
+        }
+    }
+
     // Detect Aether Native Bridge (Electron)
     if (typeof window !== 'undefined' && (window as any).aetherNative) {
         is_native = true;
@@ -132,6 +148,7 @@ export async function load({ fetch, params, parent, route, url }) {
             if (native_device_config) {
                 if (log_lvl) console.log('ROOT LOAD: Native device config received:', native_device_config);
                 // Map native device config to the expected result structure
+                // Use native as source of truth if available
                 result = {
                     ...native_device_config,
                     // Ensure naming consistency
@@ -179,10 +196,10 @@ export async function load({ fetch, params, parent, route, url }) {
         }
     }
 
-    // Perform standard FQDN lookup if not native or if native fetch failed
+    // 2. SLOW PATH: Wait for API site lookup only if we have no result yet
     if (!result) {
         try {
-            if (log_lvl) console.log(`ROOT LOAD: Starting site lookup V3 for ${fqdn}...`);
+            if (log_lvl) console.log(`ROOT LOAD: No cache. Starting site lookup V3 for ${fqdn}...`);
             
             // Use dedicated Agent Key for Bootstrap and include the unauthenticated bypass header ONLY for this request
             const bootstrap_api_cfg = { 
@@ -206,6 +223,15 @@ export async function load({ fetch, params, parent, route, url }) {
             console.error(`ROOT LOAD: Site lookup critical failure for ${fqdn}.`, err);
             api_error = true;
         }
+    } else {
+        // We have a result (cache or native), fire off the refresh in the background to update Dexie
+        if (log_lvl) console.log('ROOT LOAD: Result already obtained. Background refresh triggered.');
+        lookup_site_domain_v3({
+            api_cfg: ae_api_init,
+            fqdn,
+            view: 'base',
+            log_lvl: 0
+        });
     }
 
     // Defensive check: if result is false (common from API helper) or null, use emergency ghost