Modular LaTeX CV: scaffolding, 13 chapters, altacv styling

Replace the monolithic ODT with a modular LaTeX source tree that becomes
the canonical full CV:

- preamble.tex: altacv color/font overrides + compact-row macros
  (\cvrow, \cvgrant, \cvtalk, \cvalum, \cvpub) so dense lists keep
  baseline-aligned dates without the tabularx misalignment the
  custom v1 had.
- cv-full.tex: driver including the 13 chapters in order.
- chapters/*.tex: header, positions, education, grants, teaching,
  examinations, service, talks, collaborators, alumni, publications,
  products (solo-founded flyRoom + Berengar), software.
- tex-vendor/altacv.cls (v1.7.4): vendored, not in TeX Live.
- Makefile: dockerised xelatex build via texlive/texlive:latest,
  with TEXINPUTS=.:./tex-vendor: so the vendored class resolves.

Output: 6-page build/cv-full.pdf (down from 10 in the first pass).

chapters/alumni.tex

@@ -0,0 +1,12 @@
+% Chapter: Alumni
+\cvsection{Alumni}
+
+\cvalum{Laurence Blackhurst (PhD 2024)}{Research fellow at L2D, UK}
+\cvalum{Federica Falconio (PhD 2024)}{Field Application Scientist at SPT, UK}
+\cvalum{Michaela Joyce (PhD 2023)}{Postdoc at the Crick Institute, UK}
+\cvalum{Hannah Jones (PhD 2022)}{Postdoc at the University of Cologne, DE}
+\cvalum{Alice French (postdoc 2021)}{Lecturer at the University of Bristol, UK (ERC Starting Grant)}
+\cvalum{Esteban Beckwith (postdoc 2020)}{Assistant Professor at University of Buenos Aires, Argentina (Wellcome DA)}
+\cvalum{Diana Bicazan (PhD 2019)}{Research scientist, Reevo, UK}
+\cvalum{Quentin Geissmann (PhD 2018)}{Assistant Professor at Aarhus University, Denmark}
+\cvalum{Anne Petzold (PhD 2017)}{Assistant Professor at the European Neuroscience Institute, Germany}