Move keep_initramfs logic into add_bootloader()

The grub-btrfs snapshot detection was in guided.py, forcing custom
script authors to replicate it. Since Installer already holds
disk_config, the check belongs inside add_bootloader().

archinstall/lib/installer.py

@@ -1806,7 +1806,6 @@ class Installer:
 		bootloader: Bootloader,
 		uki_enabled: bool = False,
 		bootloader_removable: bool = False,
-		keep_initramfs: bool = False,
 	) -> None:
 		"""
 		Adds a bootloader to the installation instance.
@@ -1856,6 +1855,12 @@ class Installer:
 				bootloader_removable = False
 
 		if uki_enabled:
+			keep_initramfs = (
+				bootloader == Bootloader.Grub
+				and self._disk_config.has_default_btrfs_vols()
+				and self._disk_config.btrfs_options is not None
+				and self._disk_config.btrfs_options.snapshot_config is not None
+			)
 			self._config_uki(root, efi_partition, keep_initramfs)
 
 		match bootloader:

archinstall/scripts/guided.py

@@ -115,21 +115,10 @@ def perform_installation(
 			installation.setup_swap(algo=config.swap.algorithm)
 
 		if config.bootloader_config and config.bootloader_config.bootloader != Bootloader.NO_BOOTLOADER:
-			keep_initramfs = False
-			if (
-				config.bootloader_config.uki
-				and config.bootloader_config.bootloader == Bootloader.Grub
-				and disk_config.has_default_btrfs_vols()
-				and disk_config.btrfs_options
-				and disk_config.btrfs_options.snapshot_config
-			):
-				keep_initramfs = True
-
 			installation.add_bootloader(
 				config.bootloader_config.bootloader,
 				config.bootloader_config.uki,
 				config.bootloader_config.removable,
-				keep_initramfs,
 			)
 
 		if config.network_config: