Migrate Python guidelines from Poetry to uv

CHANGELOG.md

@@ -7,6 +7,27 @@ ships documents, so it uses the same `v#` scheme as the documents themselves.
 Individual guideline documents carry their own `Document Version` header, and the skills carry
 `metadata.version`; both are independent of the revisions below.
 
+## v10 — 2026-10-13
+
+### Changed
+- **Python tooling moved from Poetry to uv** — `Python/DESIGN_DOCUMENT_PYTHON.md` v11 → v12 and
+  `Python/DESIGN_DOCUMENT_PYTHON_MODULE.md` v4 → v5. Section 11 is now "uv": `uv sync`, `uv add`,
+  `uv add --dev`, `uv remove`, `uv run`, and for libraries `uv build` / `uv publish`. The lock file is
+  `uv.lock`, with the same rule as before — committed for applications, ignored for libraries
+- uv also manages the interpreter — section 11 gained `uv python install <version>` and states that
+  the interpreter is a uv-managed Python, no pyenv and no system Python
+- The application document's new text is taken from the copy already migrated by hand in Curator, so
+  that copy and the master are one and the same v12
+- Library `pyproject.toml` example uses the `uv_build` backend in place of `poetry-core`. The
+  `[tool.poetry] packages` table is gone — `uv_build` finds `src/<name>/` by itself — and the ban on
+  entry points now names `[project.scripts]`
+- `Python/TEMPLATE.md`, `Python/.gitignore` and the README conventions line follow: `uv.lock` in place
+  of `poetry.lock`
+- `Zscaler/ZSCALER_CERTIFICATE.md` — uv does not read `REQUESTS_CA_BUNDLE`, so it moved to the
+  `SSL_CERT_FILE` row; the verification command is `uv run`
+
+---
+
 ## v9 — 2026-10-07
 
 ### Added