docs: Dissertation, GitHub-Repo, Website und LinkedIn von Stefan Sechelmann ergänzt

README:
- Neuer Einstieg mit vollständiger Dissertation-Referenz (Titel, TU Berlin 2016,
  DOI 10.14279/depositonce-5415, CC BY-SA 4.0)
- Links zu Original-Java-Repo, sechel.de und linkedin.com/in/sechel
- Neuer Abschnitt "Ursprung & Danksagung" vor der Lizenz

doc/architecture/overall_pipeline.md:
- Neuer "Origin"-Abschnitt ganz oben mit vollständiger Quellenangabe
- Literaturabschnitt erweitert: Dissertation als "Primary source" hervorgehoben,
  Java-Original-Repo als direkter Port-Bezug dokumentiert

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

doc/architecture/overall_pipeline.md

@@ -1,5 +1,31 @@
 # conformallab++ — Architecture & Pipeline
 
+## Origin
+
+conformallab++ is a C++ reimplementation of
+[ConformalLab](https://github.com/varylab/conformallab),
+the Java research library for discrete conformal geometry by
+**Stefan Sechelmann** (TU Berlin, Institut für Mathematik,
+SFB/Transregio 109 *Discretization in Geometry and Dynamics*).
+
+The algorithmic foundation is his doctoral dissertation:
+
+> Stefan Sechelmann —  
+> **Variational Methods for Discrete Surface Parameterization: Applications and Implementation**  
+> Doctoral thesis, Technische Universität Berlin, 2016.  
+> DOI: [10.14279/depositonce-5415](https://depositonce.tu-berlin.de/items/8e2988b2-d991-45b5-aad5-9fb7988f3b2f) · CC BY-SA 4.0
+
+The dissertation develops the variational framework for discrete conformal equivalence:
+discrete uniformization of Riemann surfaces, cone metrics, period matrices, and
+holonomy — all of which are directly implemented in this library.
+
+Further links:  
+**Java original:** [github.com/varylab/conformallab](https://github.com/varylab/conformallab) ·
+**Website:** [sechel.de](https://sechel.de/) ·
+**LinkedIn:** [linkedin.com/in/sechel](https://www.linkedin.com/in/sechel/)
+
+---
+
 ## Positioning
 
 conformallab++ is a **specialised research library for discrete conformal geometry** on
@@ -447,6 +473,15 @@ This mirrors exactly the contract table in this document.
 
 ## Recommended reading
 
+### Primary source — the dissertation this library implements
+
+| | |
+|---|---|
+| **Sechelmann** — *Variational Methods for Discrete Surface Parameterization: Applications and Implementation*, TU Berlin 2016 | The mathematical foundation of the entire library: discrete conformal equivalence, variational angle-sum functionals, Newton solver, uniformization, period matrices. DOI: [10.14279/depositonce-5415](https://depositonce.tu-berlin.de/items/8e2988b2-d991-45b5-aad5-9fb7988f3b2f) |
+| **Java original** — [github.com/varylab/conformallab](https://github.com/varylab/conformallab) | Reference implementation in Java — the direct source for all algorithms ported to C++ |
+
+### Further references
+
 | Source | Relevance in conformallab++ |
 |--------|----------------------------|
 | Springborn — *Ideal Hyperbolic Polyhedra and Discrete Uniformization* (2020) | HyperIdeal functional; ζ₁₃/ζ₁₄/ζ₁₅ in `hyper_ideal_geometry.hpp` |