Perf: replace JSON.stringify comparisons with efficient identity checks

JSON.stringify on large store objects (ae_loc, ae_api, slct, event lists)
was running on every navigation, comparing serialized strings of potentially
deep objects. Replace with targeted comparators:

- Root +layout.svelte: add shallow_equal() helper — O(n keys) key-by-key
  identity check instead of O(serialized bytes). Used for ae_api, ae_loc,
  and slct sync guards.

- Launcher +layout.svelte: ID-list join-compare for event_location_obj_li
  and id_li__event_location (O(n) string vs O(n*m) stringify). Refactor
  liveQuery closures to be pure (data-only, no store reads/writes inside
  the async Dexie context where Svelte reactivity tracking is undefined).
  Move store sync into separate $effects that compare updated_on + id
  (O(1)) or ID-join (O(n)) rather than full object serialization.

src/routes/+layout.svelte

@@ -2,7 +2,7 @@
     /** @type {import('./$types').LayoutData} */
     // /** @type {import('./$types').LayoutProps} */
 
-    let log_lvl: number = 1;
+    let log_lvl: number = 0;
 
     // *** Import Svelte specific
     import { untrack } from 'svelte';
@@ -71,6 +71,20 @@
 
     let last_reload_time = 0;
 
+    // Shallow equality guard — avoids triggering Svelte store updates when the merged
+    // object is functionally identical to the current one. Comparing JSON.stringify on
+    // large objects like $ae_loc (site config, device info, flags) is expensive and
+    // runs on every navigation. Key-by-key identity check is O(n keys), not O(n chars).
+    function shallow_equal(a: Record<string, any>, b: Record<string, any>): boolean {
+        const keys_a = Object.keys(a);
+        const keys_b = Object.keys(b);
+        if (keys_a.length !== keys_b.length) return false;
+        for (const k of keys_a) {
+            if (a[k] !== b[k]) return false;
+        }
+        return true;
+    }
+
     // 1. CONSOLIDATED SYNC EFFECT (One single point of entry for store updates)
     $effect(() => {
         if (!browser || !ae_acct) return;
@@ -83,7 +97,7 @@
             const new_api = { ...current_api, ...(ae_acct.api || {}) };
             // Deep check for JWT specifically to avoid extra triggers
             if (current_api.jwt !== $ae_loc.jwt) new_api.jwt = $ae_loc.jwt;
-            if (JSON.stringify(current_api) !== JSON.stringify(new_api)) {
+            if (!shallow_equal(current_api, new_api)) {
                 $ae_api = new_api;
             }
 
@@ -93,13 +107,13 @@
             if (!new_loc.sys_menu) new_loc.sys_menu = { hide: false, hide_access_type: false, expand_access_type: false, hide_edit_mode: false, expand_edit_mode: false, hide_user: false, expand_user: false, hide_theme: false, expand_theme: false, hide_cfg: false, expand_cfg: false };
             if (!new_loc.debug_menu) new_loc.debug_menu = { hide: false, expand: false };
 
-            if (JSON.stringify(current_loc) !== JSON.stringify(new_loc)) {
+            if (!shallow_equal(current_loc, new_loc)) {
                 $ae_loc = new_loc;
             }
 
             const current_slct = $slct;
             const new_slct = { ...current_slct, ...(ae_acct.slct || {}) };
-            if (JSON.stringify(current_slct) !== JSON.stringify(new_slct)) {
+            if (!shallow_equal(current_slct, new_slct)) {
                 $slct = new_slct;
             }