unknown-metas reports the new 'also' meta as unknown

Problem

unknown-metas reports +also as an unknown meta, although the modern parser emits it (see add-default-package.xsl in eo-parser).

Root cause

src/main/resources/org/eolang/lints/metas/unknown-metas.xsl:15 whitelists a fixed set of meta heads (package, architect, version, home, spdx, rt, lint, tests, unlint, import, alias, compile, repo, register, system, ...) — also is not among them, so any +also ... is flagged as unknown.

Minimal example

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

[] > main

+also app is reported as an unknown meta.

Expected behavior

also should be added to the list of known metas (and kept in sync with the metas the parser can emit).

Related

• eo-parser add-default-package.xsl (introduces +also).
• Existing packs under packs/single/unknown-metas/.

Start with src/main/resources/org/eolang/lints/metas/unknown-metas.xsl:15 and compare its known-meta list with the +also output described from eo-parser's add-default-package.xsl. Review the existing packs under packs/single/unknown-metas/ and add coverage for the minimal example. Done means +also is accepted without an unknown-meta report while existing unknown metas remain flagged.