fix various over‑ and underfull hboxen and vboxen

also add copyright (from git log -p, skipping years with trivial-
only changes)

teckids2ltr.lco

+% Briefoptionen „2.0“ für den Teckids e.V.
+%
+% Copyright © 2019, 2024
+%	Thorsten Glaser <thorsten.glaser@teckids.org>
+% Copyright © 2013, 2015, 2016
+%	Dominik George <nik@naturalnet.de>
+%
+% Provided that these terms and disclaimer and all copyright notices
+% are retained or reproduced in an accompanying document, permission
+% is granted to deal in this work without restriction, including un‐
+% limited rights to use, publicly perform, distribute, sell, modify,
+% merge, give away, or sublicence.
+%
+% This work is provided “AS IS” and WITHOUT WARRANTY of any kind, to
+% the utmost extent permitted by applicable law, neither express nor
+% implied; without malicious intent or gross negligence. In no event
+% may a licensor, author or contributor be held liable for indirect,
+% direct, other damage, loss, or other issues arising in any way out
+% of dealing in the work, even if advised of the possibility of such
+% damage or existence of a defect, except proven that it results out
+% of said person’s immediate fault when using the work as intended.
+
 \hypersetup{colorlinks = false}%
 \teckidsgeometry[margin=2cm]%
-% note: not in teckids2style as some pubmats use P for RaggedRight
-\newcolumntype{P}[1]{>{\centering\arraybackslash}p{#1}}%
 
 \setkomavar{signature}{\errmessage{komavar signature not set}}% ← set in each letter!
 
@@ -34,7 +54,7 @@
 
 \setkomavar{firstfoot}{%
  \parbox[t]{\textwidth}{\footnotesize%
-\begin{tabularx}{\linewidth}[t]{@{}p{.75\linewidth} P{.25\linewidth}}
+\begin{tabular}[t]{@{}p{.75\linewidth}@{}>{\centering\arraybackslash}p{.25\linewidth}@{}}
   Vereinsregister Amtsgericht Bonn · VR 9846\newline
   Vorstand: Dominik George, Tom Teichler, Benedict Suska\newline
   Stadtsparkasse KölnBonn · IBAN: \mbox{DE31 3705 0198 1933 0485 46} · BIC: \mbox{COLSDE33XXX}\newline
@@ -45,7 +65,7 @@
 
   \vspace{\baselineskip}%
   \includegraphics[height=3\baselineskip]{logo_informatik-aktuell}%
-\end{tabularx}}%
+\end{tabular}}%
 }%
 
 \@addtoplength{firstfootvpos}{-1cm}%