feat(build): refactor build script with interactive version and variant selection

Replace automatic version reading from VERSION file with interactive prompts for version (major.minor.build) and ISO variant name (e.g., cli, gnome, kde).

Changes:
- Remove automatic VERSION file reading; now serves as default with prompt
- Add interactive prompts for version and variant name with validation
- Simplify ISO naming from FWS-v{major}-{minor}-{build}-{date}-x86_64.iso to fws-{version}-{variant}.iso
- Update hostname from 'archiso' to 'fws'
- Add custom FWS logo for fastfetch with color configuration
- Improve error messages and user feedback

This enables flexible build variants and streamlines the build process.

configs/releng/airootfs/etc/hostname

@@ -1 +1 @@
-archiso
+fws

configs/releng/airootfs/etc/profile.d/fastfetch.sh

@@ -5,5 +5,14 @@
 # On utilise donc un autre nom.
 _fastfetch_rc=$?
 if [ "${_fastfetch_rc}" -eq 0 ]; then
-    fastfetch
+    # Logo FWS maison (4 carrés + Tux) au lieu du logo Arch détecté par défaut.
+    fastfetch \
+        --logo-type file \
+        --logo /usr/local/share/fws/logo.txt \
+        --logo-color-1 '38;2;30;160;100' \
+        --logo-color-2 '38;2;45;125;210' \
+        --logo-color-3 '38;2;240;180;40' \
+        --logo-color-4 '38;2;25;85;145' \
+        --logo-color-5 '38;2;28;28;34' \
+        --logo-color-6 '38;2;245;165;35'
 fi

configs/releng/airootfs/usr/local/share/fws/logo.txt

@@ -0,0 +1,9 @@
+$1████████ $2██$5████$2██
+$1████████ $2█$5██$2██$5██$2█
+$1████████ $2█$5██████$2█
+$1████████ $2██$6█$2██$6█$2██
+
+$3████████ $4████████
+$3████████ $4████████
+$3████████ $4████████
+$3████████ $4████████