targets: set DESKTOP_TIER=mid for every generated desktop build

armbian-config's module_desktops treats minimal / mid / full as
three distinct install targets (see PR armbian/build#9683 /
configng module_desktops). The build framework hard-requires an
explicit DESKTOP_TIER when BUILD_DESKTOP=yes — missing it causes
the install step to bail out of the config-prepare phase.

generate_targets.py emits 12 `desktop-*` target blocks across
the stable / legacy / edge / nightly ubuntu flavours. None of
them currently set DESKTOP_TIER, so every regenerated
targets.yaml was failing module_desktops config validation once
the build-side PR landed.

Insert `DESKTOP_TIER: "mid"` into every block (after the
existing DESKTOP_APPGROUPS_SELECTED line so the indentation
stays consistent with the rest of the vars: stanza). 'mid' keeps
the current user-facing size budget the nearest to the old
default desktop (browser + file manager + media apps, ~1 GB) —
matches what the legacy DESKTOP_APPGROUPS_SELECTED='' target
produced before the migration.

Author: igorpecovnik

scripts/generate_targets.py

@@ -902,6 +902,7 @@ def generate_stable_yaml(conf_wip_boards, manual_content=""):
       DESKTOP_ENVIRONMENT: "xfce"
       DESKTOP_ENVIRONMENT_CONFIG_NAME: "config_base"
       DESKTOP_APPGROUPS_SELECTED: "programming"
+      DESKTOP_TIER: "mid"
     items:
       - *stable-current-slow-hdmi
 """
@@ -927,6 +928,7 @@ def generate_stable_yaml(conf_wip_boards, manual_content=""):
       DESKTOP_ENVIRONMENT: "gnome"
       DESKTOP_ENVIRONMENT_CONFIG_NAME: "config_base"
       DESKTOP_APPGROUPS_SELECTED: "programming"
+      DESKTOP_TIER: "mid"
     items:
 """
         if current_fast:
@@ -955,6 +957,7 @@ def generate_stable_yaml(conf_wip_boards, manual_content=""):
       DESKTOP_ENVIRONMENT: "kde-neon"
       DESKTOP_ENVIRONMENT_CONFIG_NAME: "config_base"
       DESKTOP_APPGROUPS_SELECTED: "programming"
+      DESKTOP_TIER: "mid"
     items:
       - *stable-current-fast-hdmi
 """
@@ -980,6 +983,7 @@ def generate_stable_yaml(conf_wip_boards, manual_content=""):
       DESKTOP_ENVIRONMENT: "xfce"
       DESKTOP_ENVIRONMENT_CONFIG_NAME: "config_base"
       DESKTOP_APPGROUPS_SELECTED: "programming"
+      DESKTOP_TIER: "mid"
     items:
       - *stable-legacy-fast-hdmi
 """
@@ -1001,6 +1005,7 @@ def generate_stable_yaml(conf_wip_boards, manual_content=""):
       DESKTOP_ENVIRONMENT: "xfce"
       DESKTOP_ENVIRONMENT_CONFIG_NAME: "config_base"
       DESKTOP_APPGROUPS_SELECTED: ""
+      DESKTOP_TIER: "mid"
     items:
 """
         if current_riscv64:
@@ -1170,6 +1175,7 @@ def generate_nightly_yaml(conf_wip_boards, manual_content=""):
       DESKTOP_ENVIRONMENT: "gnome"
       DESKTOP_ENVIRONMENT_CONFIG_NAME: "config_base"
       DESKTOP_APPGROUPS_SELECTED: ""
+      DESKTOP_TIER: "mid"
     items:
       - *nightly-fast-hdmi
 """
@@ -1191,6 +1197,7 @@ def generate_nightly_yaml(conf_wip_boards, manual_content=""):
       DESKTOP_ENVIRONMENT: "xfce"
       DESKTOP_ENVIRONMENT_CONFIG_NAME: "config_base"
       DESKTOP_APPGROUPS_SELECTED: ""
+      DESKTOP_TIER: "mid"
     items:
       - *nightly-slow-hdmi
 """
@@ -1212,6 +1219,7 @@ def generate_nightly_yaml(conf_wip_boards, manual_content=""):
       DESKTOP_ENVIRONMENT: "xfce"
       DESKTOP_ENVIRONMENT_CONFIG_NAME: "config_base"
       DESKTOP_APPGROUPS_SELECTED: ""
+      DESKTOP_TIER: "mid"
     items:
       - *nightly-riscv64
 """
@@ -1453,6 +1461,7 @@ def generate_community_yaml(csc_tvb_boards, manual_content=""):
       DESKTOP_ENVIRONMENT: "gnome"
       DESKTOP_ENVIRONMENT_CONFIG_NAME: "config_base"
       DESKTOP_APPGROUPS_SELECTED: ""
+      DESKTOP_TIER: "mid"
     items:
       - *community-current-fast-hdmi
 """
@@ -1478,6 +1487,7 @@ def generate_community_yaml(csc_tvb_boards, manual_content=""):
       DESKTOP_ENVIRONMENT: "kde-neon"
       DESKTOP_ENVIRONMENT_CONFIG_NAME: "config_base"
       DESKTOP_APPGROUPS_SELECTED: ""
+      DESKTOP_TIER: "mid"
     items:
       - *community-current-fast-hdmi
 """
@@ -1503,6 +1513,7 @@ def generate_community_yaml(csc_tvb_boards, manual_content=""):
       DESKTOP_ENVIRONMENT: "xfce"
       DESKTOP_ENVIRONMENT_CONFIG_NAME: "config_base"
       DESKTOP_APPGROUPS_SELECTED: ""
+      DESKTOP_TIER: "mid"
     items:
 """
         if current_slow:
@@ -1529,6 +1540,7 @@ def generate_community_yaml(csc_tvb_boards, manual_content=""):
       DESKTOP_ENVIRONMENT: "xfce"
       DESKTOP_ENVIRONMENT_CONFIG_NAME: "config_base"
       DESKTOP_APPGROUPS_SELECTED: ""
+      DESKTOP_TIER: "mid"
     items:
 """
         if current_riscv64: