release: 2.3.1 — logo + author-metadata + tooling/docs

- Add the GenAIRR logo (transparent background) and surface it at the top
  of the README so it renders on the PyPI project page.
- Bump version 2.3.0 -> 2.3.1; add the CHANGELOG entry.

This release carries the correct PyPI author metadata (Thomas
Konstantinovsky first), the tools/build_imgt_configs.py maintainer tool,
__all__ on the public authoring modules, the codebase reorganization, and
the bundled-cartridge distribution-provenance docs note. No public API or
simulation-behaviour changes.

Author: MuteJester

CHANGELOG.md

@@ -2,6 +2,33 @@
 
 All notable changes to GenAIRR are documented here.
 
+## [2.3.1] - 2026-07-05
+
+Maintenance release. No public API or simulation-behaviour changes.
+
+### Packaging
+- Correct the PyPI author metadata (Thomas Konstantinovsky listed first).
+- Add the GenAIRR logo to the README / PyPI project page.
+
+### Added
+- `tools/build_imgt_configs.py` — a first-class maintainer tool that builds
+  structural cartridges from IMGT V-QUEST germline FASTA via
+  `ReferenceCartridgeBuilder`.
+- `__all__` on the documented public authoring modules (`reference_models`,
+  `reference_rules`, `cartridge_builder`, `genotype_priors`, `cohort`).
+
+### Changed
+- Large behaviour-preserving internal reorganization: several god-files split
+  into focused packages/modules (`experiment.py`, `_cartridge_estimators`,
+  `_compiled`, `result`, `genotype`, `utilities/visualize`, and the Rust
+  `airr_record/validate.rs`), plus dead-code and duplicate-module removal. No
+  user-visible import paths changed.
+
+### Documentation
+- Clarify that only the human IGH/IGK/IGL and TCRB cartridges carry
+  data-derived distributions; every other bundled cartridge uses
+  uniform/placeholder parameters (with guidance on fitting real ones).
+
 ## [2.3.0] - 2026-06-18
 
 ### Added - Per-individual diploid genotypes

README.md

@@ -1,3 +1,7 @@
+<p align="center">
+  <img src="https://raw.githubusercontent.com/MuteJester/GenAIRR/master/site_docs/assets/genairr_logo.png" alt="GenAIRR" width="200">
+</p>
+
 <h1 align="center">GenAIRR</h1>
 
 <p align="center">

pyproject.toml

@@ -15,7 +15,7 @@ build-backend = "maturin"
 
 [project]
 name = "GenAIRR"
-version = "2.3.0"
+version = "2.3.1"
 description = "Synthetic immune-receptor-sequence simulator for benchmarking alignment models and sequence analysis."
 readme = "README.md"
 requires-python = ">=3.9"