incorrect-spdx skips single-segment +spdx values like 'MIT'

Problem

incorrect-spdx does not check single-segment +spdx values at all — e.g. +spdx MIT (with no space-separated SPDX-...: header) is silently accepted.

Root cause

src/main/resources/org/eolang/lints/metas/incorrect-spdx.xsl:13:

<xsl:for-each select="/object/metas/meta[head='spdx' and count(part) > 1]">

The count(part) > 1 guard skips metas whose tail has a single whitespace-separated part, so +spdx MIT never reaches the validation logic.

Minimal example

+package x
+architect yegor@256.com
+version 0.0.1
+home https://github.com/objectionary
+spdx MIT
+spdx SPDX-FileCopyrightText: Copyright (c) 2026 Objectionary.com
+spdx SPDX-License-Identifier: MIT

[] > main

+spdx MIT is not flagged, even though a valid SPDX meta must start with SPDX-...:.

Expected behavior

Single-part +spdx values (e.g. MIT, Apache-2.0) should be flagged as incorrect, or the guard should be reworked so the validation covers them.

Related

• metas/mandatory-spdx.xsl — sibling rule.
• Existing packs under packs/single/incorrect-spdx/.

Start with src/main/resources/org/eolang/lints/metas/incorrect-spdx.xsl, especially the selection at line 13, and compare it with the sibling metas/mandatory-spdx.xsl rule. Inspect the existing packs under packs/single/incorrect-spdx/ and verify that single-part values such as MIT and Apache-2.0 are flagged while valid SPDX-prefixed values remain accepted.