feat(python): add native distribution and release infrastructure

- add the Rust-backed Python API with PyStemmer compatibility
- distribute standard compiled models as a separate Python package
- generate model artifacts during builds instead of storing them in Git
- add GitHub release and Pages-backed package index workflows
- add Python tests, benchmarks, documentation, and Gradle integration
- refresh the documentation site, branding, and language benchmarks

python/models-standard/README.md

@@ -0,0 +1,26 @@
+# Radixor standard models
+
+This pure-Python distribution supplies Radixor's 20 precompiled standard
+language models. It is installed automatically by `pip install radixor`; users
+normally do not import it directly.
+
+The catalog version is `2026.1`. Individual model versions recorded in the
+generated `radixor_models_standard/manifest.json` are currently `1.0.0`. The
+optional Polish PoliMorf model is intentionally not part of the standard
+catalog.
+The first Python model distribution is released as `1.0.0`; its version is
+independent of both the catalog identity and the individual model versions.
+The checked-in descriptors use `0.0.0` as a deliberate non-release placeholder.
+The release workflow creates an isolated project below `build/`, injects the Git
+tag version, and deterministically compiles all model resources there.
+
+Only gzip-compressed Radixor v7 (`.rxc`) tries are shipped. They are release
+artifacts, not checked-in repository files. Canonical textual dictionaries
+remain in the Radixor source repository and are not included in this wheel or
+source distribution. Model data is licensed under CC BY-SA 3.0; see
+`LICENSE-MODEL-DATA.txt` and the generated per-model notices.
+
+The checked-out directory is intentionally only a packaging skeleton and is
+not directly buildable as the complete data distribution. From the repository
+root, use `./gradlew pythonBuildStandardModels`; the generated project and its
+wheel/sdist are written below `build/python/`.