Add new_tex_uwletter script and update README

Add new_tex_uwletter script (moved from ~/bin) with bug fixes: set -e,
quoted variables, WORK_DIR instead of TMPDIR, existence check for
destination, and mktemp inside the conditional. Update README to fix
stale URLs, ShareLaTeX -> Overleaf, MacOSX -> macOS, typo in
Dasgupta's email, and add script usage section.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

README

@@ -1,3 +1,10 @@
+================================
+=== UW LaTeX Letterhead ========
+================================
+
+Copyright (c) 2018-2026 Benjamin Mako Hill <mako@atdot.cc> / <makohill@uw.edu>
+Copyright (c) 2017 Sayamindu Dasgupta <sdg1@uw.edu>
+
 This is a LaTeX version of the University of Washington "matrix"
 stationery or letterhead.
 
@@ -10,53 +17,84 @@ Services.
 Requirements
 =============
 
-Because this document requires an OpenType and a TrueType fonts, you
-will need use to XeTeX—a modern TeX compiler. It is supported by
-https://sharelatex.com/ although it not the default. It should be
-installable on GNU/Linux, Windows, and MacOSX. More details are
-available here: https://tug.org/xetex/
+Because this document uses OpenType and TrueType fonts, it requires
+XeTeX rather than standard LaTeX. It is supported by Overleaf
+(https://overleaf.com/) although it is not the default. More details
+on XeTeX are available here: https://tug.org/xetex/
 
-A number of the normal LaTeX font packages will not work with
-XeLaTeX. For more information, see http://xetex.sourceforge.net/
+On Debian or Ubuntu, install the following packages:
 
-The two required fonts Matrix-II And OpenSans are both included in
-this repository.
+* latexmk
+* texlive-xetex
+* texlive-latex-recommended
+* texlive-latex-extra
 
-There is a makefile included which allows you to run `make pdf` to
-build the PDF and `make clean` to clean up from a build. Running this
-will required:
+  apt install latexmk texlive-xetex texlive-latex-recommended \
+  texlive-latex-extra
 
-* GNU Make: https://www.gnu.org/software/make/
-* latexmk: https://ctan.org/pkg/latexmk?lang=en
+On other systems, installing a full TeX Live distribution should
+provide everything needed.
+
+The two required fonts Matrix-II and OpenSans are both included in
+this repository, so no additional font packages are needed.
 
 
-Encrypted signatures files
+Encrypted signature files
 ===========================
 
 If you'd like, you can encrypt the signature file. There are several
-lines you in the Makefile you can uncomment to do this. We've included
-an optional encrypted copy of the fake signature file. To use it, the
+lines in the Makefile you can uncomment to do this. We've included an
+optional encrypted copy of the fake signature file. To use it, the
 passphrase is "weakpassword" (without quotes). You will want to
-customize this. To use this, you will also need the GNU Privacy Guard
+customize this. To use this, you will also need GNU Privacy Guard
 (GPG) installed on your system.
 
 
+Scripts
+========
+
+new_tex_uwletter
+-----------------
+Creates a new letter directory from the template. Takes a destination
+directory as its argument:
+
+  new_tex_uwletter <directory>
+
+Example:
+
+  new_tex_uwletter my-letter
+
+This creates my-letter/ populated with the template files, with the
+main source file renamed to my-letter.tex. Fonts are symlinked from
+the source repository rather than copied, so the repository must
+remain in place.
+
+Symlink the script into your PATH with:
+
+  ln -s ~/tex/uw_tex_letterhead/new_tex_uwletter ~/bin/
+
+
 Contributing changes
 =======================
 
-If you notice issues with this template, please fix them contribute
-back a patch so others can use them!
+If you notice issues with this template, please fix them and
+contribute back a patch so others can benefit!
 
-You can always find the latest version at the following URL:
+The latest version can be found at:
+https://gitea.communitydata.science/mako/uw_tex_letterhead
 
-https://code.communitydata.cc/uw_tex_letterhead.git
+You can clone the repository with:
 
-Information on contributing back can be found here:
+  git clone https://gitea.communitydata.science/mako/uw_tex_letterhead.git
 
-https://code.communitydata.cc/
+Patches can be submitted by email to Benjamin Mako Hill:
 
-Please email any changes, or questions, to Benjamin Mako Hill at
-makohill@uw.edu.
+  Benjamin Mako Hill <makohill@uw.edu> [work]
+  Benjamin Mako Hill <mako@atdot.cc> [personal]
+
+
+  git format-patch origin/master
+  git send-email *.patch
 
 
 Copyright and Usage
@@ -70,26 +108,17 @@ https://www.washington.edu/brand/templates/stationery/
 It is hopefully obvious that there are many ethical and legal
 restrictions on when one can and cannot (and should or shouldn't) use
 official university letterhead (e.g., it should only be used for
-official communication).
+official communication). If you have any questions, contact UW Brand
+and Creative Services at the link above.
 
-If you have any questions, you should contact UW Brand and Creative
-Services at the contact information available at the link above.
-
-This TeX template itself was created, and is copyright, by:
-
-  (c) 2018 Benjamin Mako Hill <makohill@uw.edu>
-  (c) 2017 Sayamindu Dasgupta <sdg1@uw.ed>
-
-We dedicated the work to the public domain by waiving all of our
+This TeX template itself was created by Benjamin Mako Hill and
+Sayamindu Dasgupta. We dedicated the work to the public domain by waiving all of our
 rights to the work worldwide under copyright law, including all
-related and neighboring rights, to the extent allowed by law.  You can
+related and neighboring rights, to the extent allowed by law. You can
 copy, modify, distribute and perform the work, even for commercial
 purposes, all without asking permission.
 
-See details here:
-
-https://creativecommons.org/publicdomain/zero/1.0/
+See details here: https://creativecommons.org/publicdomain/zero/1.0/
 
 As a result, if you completely remove the UW branding, there are no
-restrictions in how you can or cannot use the work in this repository.
-
+restrictions on how you can use the work in this repository.