Qubes 4.2 download, menu and updater changes

[eloquence]

• Point to Qubes 4.2.1 ISO
• Update menu refrences consistent with the new Q menu
• Describe updater consistent with its new GUI

The new Q menu is fairly complex, and describing it in text alone is tricky. To recap:

• There's a vertical section with icons for search, domains, favorites, and system
• For domains, there's a horizontal sub-section "APPS | TEMPLATES | SERVICE".
• The menu always opens in the domains section
• The selection of "APPS", "TEMPLATES" or "SERVICE" is persistent when you open and close the menu

I've therefore adopted the following conventions:

• When the user needs to switch to the system section, indicate this with ⚙️
• When the user needs to operate on domains, always indicate whether they need to be in the APPS, TEMPLATES or SERVICE sub-section, because the menu may be on a different sub-section when they open it
• I'm not indicating explicitly when the user needs to be in the "Domains" section, since the menu always opens on that section

Refs #221

[eloquence]

The build error is due LaTeX stumbling over the ⚙️ character. If we want to keep it, that's probably fixable (change the branch in deploy/Dockerfile and debug builds with podman build -t sdwdocs -f deploy/Dockerfile .); otherwise I'd suggest changing that to "Gear symbol".

[legoktm]

The build error is due LaTeX stumbling over the ⚙️ character. If we want to keep it, that's probably fixable (change the branch in deploy/Dockerfile and debug builds with podman build -t sdwdocs -f deploy/Dockerfile .); otherwise I'd suggest changing that to "Gear symbol".

Via https://github.com/sphinx-doc/sphinx/issues/10469 I found https://www.sphinx-doc.org/en/master/usage/configuration.html#confval-latex_engine - I can experiment with that a bit before giving up on unicode.

[legoktm]

Unfortunately switching to xelatex is only half of the solution, then we need to find a font that supports the gear icon (⚙ (U+2699)) in bold. Neither Noto nor DejaVu Serif have it. For some reason trying to set \setmainfont{Noto Color Emoji} doesn't work. Using Symbola does though, but I'm not super impressed with the rest of that font's quality.

diff --git a/deploy/Dockerfile b/deploy/Dockerfile
index e434507..f27947f 100644
--- a/deploy/Dockerfile
+++ b/deploy/Dockerfile
@@ -1,7 +1,8 @@
 FROM debian:bookworm AS sphinx

 ARG GIT_BRANCH=main
-RUN apt-get -q update && apt-get -qy upgrade && apt-get -qy install git make latexmk texlive-latex-extra python3-poetry
+RUN apt-get -q update && apt-get -qy upgrade && apt-get -qy install git make latexmk texlive-xetex texlive-latex-extra python3-poetry \
+    fonts-freefont-otf font-symbola texlive-fonts-extra-links
 COPY ./ .
 RUN poetry install
 RUN deploy/build $GIT_BRANCH
diff --git a/docs/conf.py b/docs/conf.py
index 4a59811..a105b6e 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -160,7 +160,13 @@ htmlhelp_basename = 'SecureDropWorkstationdoc'

 # -- Options for LaTeX output ---------------------------------------------

+latex_engine = 'xelatex'
 latex_elements = {
+    'fontpkg': r'''
+\setmainfont{DejaVu Serif}
+\setsansfont{DejaVu Sans}
+\setmonofont{DejaVu Sans Mono}
+''',
     # The paper size ('letterpaper' or 'a4paper').
     #
     # 'papersize': 'letterpaper',
@@ -177,7 +183,6 @@ latex_elements = {
     # seem to make this magically work, so define individual characters.
     'preamble': r'''
     \usepackage{amssymb}
-    \DeclareUnicodeCharacter{25B8}{$\blacktriangleright$}
     '''

     # Latex figure (float) alignment

I'm out of timebox so I'm going to say that we won't be able to use a gear emoji for the 1.0.0 release. We should aim to switch to xelatex or another Unicode supporting rendering engine though.

[legoktm]

(I've copied the above thread to https://github.com/freedomofpress/securedrop-docs/issues/576 so we don't forget about this)

[eloquence]

Most of this was incorporated into #228 (thanks :); I spotted a couple of menu references that still need to be updated, will open a smaller PR for those.