chore/docs: Onboarding-Sprint für externe Mathematiker

- LICENSE: Copyright Tarik Moussa <Tarik.moussa95@gmail.com> (war user2595)
- CITATION.cff: maschinenlesbares Zitat mit 3 Primärreferenzen (Sechelmann 2016,
  Springborn 2020, Bobenko–Springborn 2004)
- scripts/try_it.sh: Clone→Build→Test→Beispiel in einem Skript
- doc/math/software-landscape.md: Landkarte aller relevanten Tools,
  Problem-A vs. Problem-B Abgrenzung, vollständige Feature-Matrix
- doc/math/novelty-statement.md: formales Alleinstellungsmerkmal,
  Zielgruppen, was dieses Projekt nicht ist
- code/CMakeLists.txt: cmake --install Target für Header-only-Library
- doc/getting-started.md: Testzähler 158→173, Beispiel-Output, try_it.sh
- README.md: CI/License/DOI-Badges, Cite-Abschnitt, Issue-Tracker-Link,
  Copyright, neue Doku-Einträge software-landscape + novelty-statement

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

code/CMakeLists.txt

@@ -126,3 +126,17 @@ endif()
 
 # ── Tests (always) ────────────────────────────────────────────────────────────
 add_subdirectory(tests)
+
+# ── Install target (header-only library) ──────────────────────────────────────
+# Installs all public headers to <prefix>/include/conformallab/
+# Usage from another CMake project:
+#   cmake --install build --prefix /usr/local
+#   target_include_directories(myapp PRIVATE /usr/local/include/conformallab)
+include(GNUInstallDirs)
+install(DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/include/
+        DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/conformallab
+        FILES_MATCHING PATTERN "*.hpp"
+        PATTERN "* 2.*" EXCLUDE)   # exclude macOS Finder duplicates
+install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/../LICENSE
+              ${CMAKE_CURRENT_SOURCE_DIR}/../CITATION.cff
+        DESTINATION ${CMAKE_INSTALL_DATADIR}/conformallab)