feat: import MyST swap mechanism + content for sagitta (replaces #1886)

Replaces the broken #1886 with a fresh, properly-converted MyST set for
the sagitta (1.4.x) docs, mirroring what landed for circinus via #1897.

This PR:

- Re-imports 210 md-*.md files for sagitta. Source: ran the pipelines
  rst-to-myst converter (chrisjsewell/rst-to-myst v0.4.0, with pandoc
  fallback) on sagittas RST. Post-processed via the pipelines
  postprocess stage (10 ordered fixes for blanks, admonitions, label
  hyphens, pandoc artifacts, structural blanks, linter markers).
  Compared to the broken #1886 content (which was left over from an
  earlier stage-1-only run): zero raw `<div class=>` remnants.

- For 23 stems where sagittas RST is byte-identical with currents RST
  (mostly stable policy/protocol pages and the 404 page), reuses currents
  already-validated md-*.md content rather than re-converting.

- Drops cli and installation/cloud/aws from sagittas swap set: their
  RST has SEVERE/4 "Title level inconsistent" errors that crash
  rst-to-myst; they need an independent RST-source fix and are kept as
  RST-only for now.

- Adds the per-page swap mechanism: scripts/swap_sources.py,
  scripts/import_myst.py, the matching tests under tests/, _swap.txt
  with 210 stems, _ext/vyos.py MyST renderer fallback, Makefile
  swap-wrapped targets, .readthedocs.yml swap pre/post hooks.

- Adds 187 .webp images and removes 235 superseded .jpg/.png/.jpeg
  static assets; flips html_logo to vyos-logo.webp.

- Adds the MyST swap-related blocks to docs/conf.py only:
  myst_enable_extensions, myst_fence_as_directive, md-*.md exclude
  patterns, _swap_exclude.txt reader, _prefer_webp and _copy_md_sources
  setup hooks. github_version fallback set to 'sagitta' to match the
  branch (parallel to currents 'current' and circinuss 'circinus').

Deliberately excluded (per user direction):

- llms.txt and sphinx-llms-txt / sphinx-sitemap config: these will
  land separately for sagitta via #1870 plus a new sagitta-specific
  llms.txt template PR. The conf.py here does not pull those extensions
  in, so the build does not depend on the new pip packages.

Verification before pushing:

- 210 md-*.md = 210 _swap.txt stems = 210 RST siblings on sagitta (1:1:1).
- 0 files contain raw `<div class=` (the breakage that took down /en/1.5/).
- conf.py copyright/version/release preserve sagittas values
  (2024 / 1.4 / "1.4.x (sagitta)") - not currents.
- html_title from currents conf.py removed - PR #1880 is the right place
  for sagittas branch-localized title.

Supersedes / closes on merge:

- #1886 (broken converter output, would break /en/1.4/ if merged).

Generated by robots https://vyos.io

1 files changed, 40 insertions, 13 deletions

diff --git a/docs/_include/interface-ipv6.txt b/docs/_include/interface-ipv6.txt
index 0c222d80..1d3b741b 100644
--- a/docs/_include/interface-ipv6.txt
+++ b/docs/_include/interface-ipv6.txt
@@ -1,4 +1,7 @@
-.. cfgcmd:: set interfaces {{ var0 }} <interface> {{ var2 }} {{ var3 }}
+::::{cfgcmd} set interfaces {{ var0 }} \<interface\> {{ var2 }} {{ var3 }}
+
+::::
+
   {{ var5 }} {{ var6 }} ipv6 address autoconf
 
   :abbr:`SLAAC (Stateless Address Autoconfiguration)` :rfc:`4862`. IPv6 hosts
@@ -9,9 +12,11 @@
   its configuration parameters; routers respond to such a request with a router
   advertisement packet that contains Internet Layer configuration parameters.
 
-  .. note:: This method automatically disables IPv6 traffic forwarding on the
-    interface in question.
+  :::{note}
+  This method automatically disables IPv6 traffic forwarding on the
 
+  interface in question.
+  :::
   Example:
 
   .. code-block:: none
@@ -19,7 +24,10 @@
     set interfaces {{ var0 }} {{ var1 }} {{ var2 }} {{ var4 }} {{ var5 }} {{ var7 }} ipv6 address autoconf
 
 
-.. cfgcmd:: set interfaces {{ var0 }} <interface> {{ var2 }} {{ var3 }}
+::::{cfgcmd} set interfaces {{ var0 }} \<interface\> {{ var2 }} {{ var3 }}
+
+::::
+
   {{ var5 }} {{ var6 }} ipv6 address eui64 <prefix>
 
   :abbr:`EUI-64 (64-Bit Extended Unique Identifier)` as specified in
@@ -31,7 +39,10 @@
 
     set interfaces {{ var0 }} {{ var1 }} {{ var2 }} {{ var4 }} {{ var5 }} {{ var7 }} ipv6 address eui64 2001:db8:beef::/64
 
-.. cfgcmd:: set interfaces {{ var0 }} <interface> {{ var2 }} {{ var3 }}
+::::{cfgcmd} set interfaces {{ var0 }} \<interface\> {{ var2 }} {{ var3 }}
+
+::::
+
   {{ var5 }} {{ var6 }} ipv6 address no-default-link-local
 
   Do not assign a link-local IPv6 address to this interface.
@@ -42,7 +53,10 @@
 
     set interfaces {{ var0 }} {{ var1 }} {{ var2 }} {{ var4 }} {{ var5 }} {{ var7 }} ipv6 address no-default-link-local
 
-.. cfgcmd:: set interfaces {{ var0 }} <interface> {{ var2 }} {{ var3 }}
+::::{cfgcmd} set interfaces {{ var0 }} \<interface\> {{ var2 }} {{ var3 }}
+
+::::
+
   {{ var5 }} {{ var6 }} ipv6 disable-forwarding
 
   Configure interface-specific Host/Router behaviour. If set, the interface will
@@ -54,7 +68,10 @@
 
     set interfaces {{ var0 }} {{ var1 }} {{ var2 }} {{ var4 }} {{ var5 }} {{ var7 }} ipv6 disable-forwarding
 
-.. cfgcmd:: set interfaces {{ var0 }} <interface> {{ var2 }} {{ var3 }}
+::::{cfgcmd} set interfaces {{ var0 }} \<interface\> {{ var2 }} {{ var3 }}
+
+::::
+
   {{ var5 }} {{ var6 }} ipv6 adjust-mss <mss | clamp-mss-to-pmtu>
 
   As Internet wide PMTU discovery rarely works, we sometimes need to clamp our
@@ -62,16 +79,23 @@
   a SYN packet. By setting the MSS value, you are telling the remote side
   unequivocally 'do not try to send me packets bigger than this value'.
 
-  .. note:: This command was introduced in VyOS 1.4 - it was previously called:
-    ``set firewall options interface <name> adjust-mss6 <value>``
+  :::{note}
+  This command was introduced in VyOS 1.4 - it was previously called:
 
-  .. hint:: MSS value = MTU - 40 (IPv6 header) - 20 (TCP header), resulting in
-    1432 bytes on a 1492 byte MTU.
+  ``set firewall options interface <name> adjust-mss6 <value>``
+  :::
+  :::{hint}
+  MSS value = MTU - 40 (IPv6 header) - 20 (TCP header), resulting in
 
+  1432 bytes on a 1492 byte MTU.
+  :::
   Instead of a numerical MSS value `clamp-mss-to-pmtu` can be used to
   automatically set the proper value.
 
-.. cfgcmd:: set interfaces {{ var0 }} <interface> {{ var2 }} {{ var3 }}
+::::{cfgcmd} set interfaces {{ var0 }} \<interface\> {{ var2 }} {{ var3 }}
+
+::::
+
   {{ var5 }} {{ var6 }} ipv6 accept-dad <1-3>
 
   Whether to accept DAD (Duplicate Address Detection).
@@ -86,7 +110,10 @@
 
     set interfaces {{ var0 }} {{ var1 }} {{ var2 }} {{ var4 }} {{ var5 }} {{ var7 }} ipv6 accept-dad 2
 
-.. cfgcmd:: set interfaces {{ var0 }} <interface> {{ var2 }} {{ var3 }}
+::::{cfgcmd} set interfaces {{ var0 }} \<interface\> {{ var2 }} {{ var3 }}
+
+::::
+
   {{ var5 }} {{ var6 }} ipv6 dup-addr-detect-transmits <n>
 
   The amount of Duplicate Address Detection probes to send.