fix(ext): parse cmdincludemd content as RST so legacy `_include/*.txt` directives render

The `_include/*.txt` library is written in reStructuredText (`.. cfgcmd::`,
`.. code-block::`, `.. note::`, `.. cmdinclude::`). After the RST→MyST
migration, the `{cmdincludemd}` fence on .md pages routed include content
through `MockState.nested_parse`, which in MyST 2.0 simply replays the
content through the MyST renderer (see myst_parser/mocking.py:153). RST
directives in the .txt file then rendered as literal paragraph text:

  <p>.. cmdinclude:: /_include/interface-description.txt</p>
  <p>.. cfgcmd:: set interfaces ethernet ...</p>
  <p>.. code-block:: none</p>

User-visible symptom (reported on rolling docs): the Ethernet, dummy,
tunnel, bonding, bridge, macsec, vxlan, l2tpv3, pseudo-ethernet,
virtual-ethernet, and wireless pages all showed unprocessed `.. cfgcmd::`
and `.. cmdinclude::` directives instead of styled command boxes.

Fix: mirror MyST's own `{eval-rst}` plumbing
(`MockRSTParser().parse(text, doc)` per
`mdit_to_docutils/base.py:1655`). Build a fresh document that inherits
the outer document's settings + reporter, run `MockRSTParser` over the
substituted include content, and graft the resulting children back
into the calling document with explicit-target registration. Keeps the
Sphinx env available to `cfgcmd`/`opcmd`/`cmdinclude` directives.

Verified locally on rolling (Sphinx 7.x, myst-parser 2.0): zero literal
`cfgcmd::` / `cmdinclude::` / `code-block::` / `opcmd::` / `note::` /
`include::` strings remain in any built HTML page under
`configuration/`, `automation/`, `installation/`, `operation/`,
`vpp/`; all 11 affected interface pages now render proper
`cfgcmd-heading` / `cfgcmd-body` blocks (e.g. ethernet.html: 160,
wireless.html: 172, dummy.html: 4).

🤖 Generated by [robots](https://vyos.io)

(cherry picked from commit 9c815d689a2a4a5d433ba15154cb606bd986fc8d)

1 files changed, 22 insertions, 11 deletions

diff --git a/docs/_ext/vyos.py b/docs/_ext/vyos.py
index 527178d1..0c90f4bd 100644
--- a/docs/_ext/vyos.py
+++ b/docs/_ext/vyos.py
@@ -364,18 +364,29 @@ class CmdInclude(SphinxDirective):
                     line = re.sub('{{\s?var' + str(i) + '\s?}}',value,line)
             new_include_lines.append(line)
         
-        if hasattr(self.state, '_renderer'):
-            self.state._renderer.nested_render_text(''.join(new_include_lines), self.lineno)
-            return []
-        from docutils.statemachine import ViewList
-        from docutils import nodes
+        # The _include/*.txt library is written in reStructuredText
+        # (`.. cfgcmd::`, `.. code-block::`, `.. note::`, `.. cmdinclude::`).
+        # When called from a MyST `.md` page, `self.state` is MyST's
+        # MockState whose `nested_parse` just routes back through MyST —
+        # so the RST directives render as literal paragraph text.
+        #
+        # Parse the file as RST directly, mirroring what MyST itself does
+        # for `{eval-rst}` blocks (myst_parser.mocking.MockRSTParser via
+        # render_restructuredtext): build a fresh document that inherits
+        # the parent's settings (so Sphinx env / reporter survive) and
+        # graft its children back into the calling document.
+        from docutils.utils import new_document
+        from myst_parser.mocking import MockRSTParser
+
         content = ''.join(new_include_lines)
-        vl = ViewList()
-        for i, line in enumerate(content.splitlines(keepends=False)):
-            vl.append(line, include_file[1], i)
-        node = nodes.Element()
-        self.state.nested_parse(vl, self.content_offset, node, match_titles=True)
-        return node.children
+        outer_doc = self.state.document
+        newdoc = new_document(include_file[1], outer_doc.settings)
+        newdoc.reporter = outer_doc.reporter
+        MockRSTParser().parse(content, newdoc)
+        for node in newdoc.children:
+            if getattr(node, 'attributes', None) and node.get('names'):
+                outer_doc.note_explicit_target(node, node)
+        return list(newdoc.children)
 
 
 class CfgcmdlistDirective(Directive):