feat: install tools/oracle as the paperspec package

Other repositories (paperstack, then paperpack) import the reference
implementation instead of reimplementing the specification; scienting-core
will take the role later behind the same vectors.

- pyproject.toml: distribution and import name `paperspec`, version 0.1.0,
  Python >= 3.12, no base dependencies; `tools/oracle` is the package, and
  `schemas/`, `sql/` and `vectors/` ship as the data subpackages
  `paperspec.schemas`, `paperspec.sql` and `paperspec.vectors`. Extras
  `schema`, `crypto` and `tools`.
- tools/oracle/__init__.py: the Python 3.14 and cryptography/jsonschema gate
  runs only when imported as `tools.oracle` by the repository's own tools.
- crypto.py imports `cryptography` on first use of HKDF and Ed25519, with an
  ImportError naming `paperspec[crypto]`; schema.py imports `jsonschema` and
  `referencing` in `Store.validator` and `Store.registry`. package.py, db.py
  and receipts.py then import on a bare interpreter.
- pixi.toml installs the package editable (pixi.lock re-solved; no conda pin
  changed), so the tools and the package resolve to the same code.
- tools/README.md names the library surface and the extras; CHANGELOG.md
  records the packaging change under 0.1.0, since check.py requires the
  changelog's first heading to equal the format version.

No computed value, vector, fixture, schema or SQL file changed.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

pyproject.toml

@@ -0,0 +1,49 @@
+[build-system]
+build-backend = "setuptools.build_meta"
+
+requires = ["setuptools>=77"]
+
+[project]
+name = "paperspec"
+version = "0.1.0"
+description = "The scienting formats: the reference implementation of every rule, with the JSON Schemas, SQL and test vectors as package data"
+readme = "README.md"
+license = "Apache-2.0"
+license-files = ["LICENSE.md"]
+authors = [{ name = "Scientific Computing Studio", email = "maintainer@scient.ing" }]
+requires-python = ">=3.12"
+classifiers = [
+    "Development Status :: 3 - Alpha",
+    "Intended Audience :: Science/Research",
+    "Programming Language :: Python :: 3 :: Only",
+    "Topic :: Scientific/Engineering",
+]
+# The base package is standard library only. `schema.py` needs jsonschema and
+# `crypto.py` needs cryptography; the repository's own tools need both.
+dependencies = []
+
+[project.optional-dependencies]
+schema = ["jsonschema>=4.26", "referencing>=0.35"]
+crypto = ["cryptography>=46"]
+tools = ["paperspec[crypto,schema]"]
+
+[project.urls]
+Homepage = "https://paperspec.scient.ing"
+Repository = "https://git.scient.ing/infra/paperspec"
+Documentation = "https://paperspec.scient.ing/docs/"
+
+# `tools/oracle` is the package `paperspec`; the schemas, SQL and vectors travel
+# with it as data subpackages, so a consumer reads them with importlib.resources.
+[tool.setuptools]
+packages = ["paperspec", "paperspec.schemas", "paperspec.sql", "paperspec.vectors"]
+
+[tool.setuptools.package-dir]
+"paperspec" = "tools/oracle"
+"paperspec.schemas" = "schemas"
+"paperspec.sql" = "sql"
+"paperspec.vectors" = "vectors"
+
+[tool.setuptools.package-data]
+"paperspec.schemas" = ["*.json"]
+"paperspec.sql" = ["*.sql"]
+"paperspec.vectors" = ["*.jsonl"]