perf: reduce startup work and fix grade analytics bar chart animation

Batch settings storage writes, tier plugin startup, lazy-load heavy UI
chunks, and optimize global search indexing. Stop tweening bar height in
grade analytics to prevent invalid negative SVG rect values.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/seqta/utils/ensureSyncableStorageDefaults.ts

@@ -37,6 +37,8 @@ const OPTIONAL_UNSET_MEANS_DEFAULT_KEYS = [
   "profile_picture_revision",
 ] as const;
 
+let defaultsEnsured = false;
+
 /**
  * Flat default map in upload shape (plugin-format only; no legacy keys).
  */
@@ -76,6 +78,8 @@ function mergePluginSettingsDefaults(
  * Never overwrites existing values. Missing plugin settings respect legacy keys.
  */
 export async function ensureSyncableStorageDefaults(): Promise<void> {
+  if (defaultsEnsured) return;
+
   const existing = await browser.storage.local.get();
   const migratedFromExisting = migrateLegacyToPluginSettings({
     ...existing,
@@ -101,4 +105,6 @@ export async function ensureSyncableStorageDefaults(): Promise<void> {
   if (Object.keys(patch).length > 0) {
     await browser.storage.local.set(patch);
   }
+
+  defaultsEnsured = true;
 }