Preserve.ini for update cleanup, Hekate UI strings, docs

- Load sd:/config/omninx/preserve.ini during update mode cleanup to skip
  delete paths that overlap user-preserved prefixes (heap-backed path list).
- Document preserve.ini in PRESERVE_INI.md, README, and INSTALLATION_PROCESS.
- Prefer Hekate wording in main.c user messages for bootloader launch/errors.
- Extend update deletion list for exefs_patches (audio_mastervolume, SaltyNX_Fixes, logo).

source/install_update.c

@@ -37,6 +37,8 @@
 // Update mode: Cleanup specific directories/files
 int update_mode_cleanup(omninx_variant_t variant) {
     (void)variant;
+    install_preserve_update_cleanup_begin();
+
     check_and_clear_screen_if_needed();
 
     set_color(COLOR_WHITE);
@@ -66,6 +68,8 @@ int update_mode_cleanup(omninx_variant_t variant) {
         misc_files_to_delete,
         NULL);
 
+    install_preserve_update_cleanup_end();
+
     set_color(COLOR_GREEN);
     gfx_printf("  Bereinigung abgeschlossen!\n");
     set_color(COLOR_WHITE);