fix(installer): parse pkglist name field, skip unresolvable pkgs, keymap confirm

pacstrap failed at line 382 because pkglist lines from pacman -Q are
'name version' and were passed whole as pacman targets (~400 'target
not found'). Parse only the first field, pre-filter against pacman -Slq
so packages missing from the live repos (local-aur) are skipped with a
warning, and fall back to an unfiltered list if pacman -Syy fails.
Keymap screen now offers a US-layout confirm before the gum filter.

airootfs/usr/local/bin/alvin-install

@@ -40,6 +40,7 @@ trap 'gum style --foreground 9 --bold "Failed at line $LINENO. See $LOG"' ERR
 die() { gum style --foreground 9 --bold "ERROR: $*"; exit 1; }
 info() { gum style --foreground 12 --bold "$*"; }
 ok() { gum style --foreground 10 --bold "$*"; }
+warn() { gum style --foreground 11 --bold "$*"; }
 
 header() {
     gum style \
@@ -85,10 +86,18 @@ screen_keymap() {
     header "Keyboard Layout"
     echo ""
     gum style --foreground 15 \
-        "Select your console keymap." \
-        "This affects passwords and the LUKS passphrase at boot."
+        "Select the keyboard layout of your physical keyboard." \
+        "This affects passwords and the LUKS passphrase at boot." \
+        "" \
+        "The default is the US layout (us)."
     echo ""
-    KEYMAP=$(localectl list-keymaps | gum filter --header "+ Keymap" --placeholder "Search keymaps...")
+    if gum confirm --affirmative "Use us (default)" --negative "Choose another layout" \
+        "Use US keyboard layout (us)?"; then
+        KEYMAP="us"
+    else
+        KEYMAP=$(localectl list-keymaps | gum filter --header "+ Keymap" --placeholder "Search keymaps...") \
+            || die "No keymap selected."
+    fi
     [[ -z "$KEYMAP" ]] && die "No keymap selected."
     loadkeys "$KEYMAP" 2>/dev/null || true
     log "Keymap: $KEYMAP"
@@ -357,15 +366,48 @@ install_pacstrap() {
 
     local pkglist="/run/archiso/bootmnt/arch/pkglist.x86_64.txt"
     local pkgs=()
+    local dropped=()
+    local filter_ok=false
 
     if [[ -f "$pkglist" ]]; then
-        while IFS= read -r pkg; do
-            [[ -z "$pkg" ]] && continue
+        # The medium's pkglist comes from `pacman -Q`: lines are "name version".
+        # Parse only the first field, then drop names not resolvable in the live
+        # session's repos (e.g. local-aur packages are not configured there).
+        info "Syncing package databases for resolvability check..."
+        if pacman -Syy --noconfirm >>"$LOG" 2>&1; then
+            declare -A available=()
+            local db_line
+            while IFS= read -r db_line; do
+                [[ -n "$db_line" ]] && available["$db_line"]=1
+            done < <(pacman -Slq 2>>"$LOG" || true)
+            (( ${#available[@]} > 0 )) && filter_ok=true
+        else
+            warn "pacman -Syy failed (see $LOG) — installing without resolvability filter."
+        fi
+
+        local line pkg
+        while IFS= read -r line; do
+            [[ -z "$line" ]] && continue
+            pkg=${line%% *}
             skip "$pkg" && continue
+            if $filter_ok && [[ -z "${available[$pkg]:-}" ]]; then
+                dropped+=("$pkg")
+                continue
+            fi
             pkgs+=("$pkg")
         done < "$pkglist"
     fi
 
+    if (( ${#dropped[@]} > 0 )); then
+        warn "Skipped ${#dropped[@]} pkglist package(s) not found in configured repos:"
+        gum style --foreground 11 "${dropped[@]/#/  - }"
+        local d
+        for d in "${dropped[@]}"; do
+            log "Pacstrap: skipped unresolvable: $d"
+        done
+    fi
+
+    # Hardcoded essentials are never filtered — they must be in allowed repos.
     for p in base linux linux-firmware linux-cachyos linux-cachyos-headers \
              networkmanager grub efibootmgr sudo git intel-ucode amd-ucode \
              mkinitcpio cryptsetup dosfstools e2fsprogs btrfs-progs \
@@ -378,7 +420,7 @@ install_pacstrap() {
     done
 
     info "Installing ${#pkgs[@]} packages (this may take a while)..."
-    log "Pacstrap: ${#pkgs[@]} packages"
+    log "Pacstrap: ${#pkgs[@]} packages, ${#dropped[@]} skipped"
     pacstrap "$TARGET" "${pkgs[@]}" --noconfirm 2>>"$LOG"
 
     ok "Packages installed."