Make setup ISO-only

Remove legacy online installer entrypoints, collapse migrations for 4.0, and move setup responsibilities into target-side system, hardware, and user commands.

install/user/default-keyring.sh

@@ -0,0 +1,26 @@
+KEYRING_DIR="$HOME/.local/share/keyrings"
+KEYRING_FILE="$KEYRING_DIR/Default_keyring.keyring"
+DEFAULT_FILE="$KEYRING_DIR/default"
+
+mkdir -p "$KEYRING_DIR"
+
+if [[ ! -f $KEYRING_FILE ]]; then
+  cat > "$KEYRING_FILE" <<EOF
+[keyring]
+display-name=Default keyring
+ctime=$(date +%s)
+mtime=0
+lock-on-idle=false
+lock-after=false
+EOF
+fi
+
+if [[ ! -f $DEFAULT_FILE ]]; then
+  cat > "$DEFAULT_FILE" <<EOF
+Default_keyring
+EOF
+fi
+
+chmod 700 "$KEYRING_DIR"
+chmod 600 "$KEYRING_FILE"
+chmod 644 "$DEFAULT_FILE"