feat!: pin Python 3.14 and Unicode 16.0, and make the tools commands

Python and Unicode
- requires-python is >=3.14,<3.15: 3.14 is the only Python with the
  Unicode 16.0 data the specification pins (3.13 has 15.1, 3.15 has 17.0).
- `import paperspec` raises ImportError unless unicodedata reports
  paperspec.UNICODE_VERSION (16.0.0), so a source checkout or an install
  that bypasses requires-python cannot compute values on other data.

Commands
- tools/{check,build,validate,load,stress,site}.py move with history to
  src/paperspec/cli/ and install as paperspec-check, -build, -validate,
  -load, -stress and -site; each also runs as `python -m paperspec.cli.X`.
- paperspec.cli.require() exits with "install paperspec[tools]" when
  cryptography or jsonschema is missing; paperspec.cli.checkout() finds
  the repository the check, build, stress and site commands work on (the
  editable install's own checkout, else the one around the current
  folder) and exits with a message outside one. tools/__init__.py is gone.
- validate and load read the schemas and SQL through the new
  paperspec.resources.path(), which finds them in a wheel and in an
  editable install alike, so they work anywhere the package is installed.
- check runs the rebuild as `python -m paperspec.cli.build`.
- build still writes the provenance tool label "paperspec tools/build.py":
  it is part of every hashed and signed fixture.
- pixi tasks and the check workflow run the commands; tools/README.md
  documents them, and the other docs name the commands instead of paths.

License
- LICENSE.md gives `src/` Apache-2.0 alongside `tools/`. Since the
  previous commit moved the code to src/, no row had covered it.

pixi run check passes (run as `python -m paperspec.cli.check` with src/ on
the path, since this environment cannot install the entry points); the
byte-for-byte rebuild matches, so no fixture or vector changed.
pixi.lock still needs `pixi lock`.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -22,10 +22,12 @@ The first release.
 
 ### 0.1.1
 
-Packaging and lazy imports only; the formats stay at 0.1.0, and no computed value, vector, fixture, schema or SQL file changed.
+Packaging, commands and lazy imports only; the formats stay at 0.1.0, and no computed value, vector, fixture, schema or SQL file changed.
 
 - The oracle moves from `tools/oracle/` to `src/paperspec/` and installs as the Python package `paperspec` (`pyproject.toml`, setuptools), with `schemas/`, `sql/` and `vectors/` as the data subpackages `paperspec.schemas`, `paperspec.sql` and `paperspec.vectors`, so other repositories import the reference implementation instead of reimplementing it.
 - The package version comes from git tags through setuptools-scm.
-- The base package has no dependencies and requires Python 3.14, the first with the Unicode 16.0 character data the specification pins; the extras `paperspec[schema]` (`jsonschema`, `referencing`), `paperspec[crypto]` (`cryptography`) and `paperspec[tools]` (both) cover `schema` and the HKDF and Ed25519 functions of `crypto`, which now import their packages on first use.
-- The tools import `paperspec` from `src/`, and their Python 3.14 and package check moves to `tools/__init__.py`, so the package itself checks nothing on import.
+- The base package has no dependencies and requires Python 3.14, the only version with the Unicode 16.0 character data the specification pins, and refuses to import under any other Unicode version; the extras `paperspec[schema]` (`jsonschema`, `referencing`), `paperspec[crypto]` (`cryptography`) and `paperspec[tools]` (both) cover `schema` and the HKDF and Ed25519 functions of `crypto`, which now import their packages on first use.
+- `paperspec.resources.path` finds the schemas, SQL and vectors in an installed wheel and in an editable install alike.
+- The programs in `tools/` become the package's commands in `src/paperspec/cli/`: `paperspec-check`, `paperspec-build`, `paperspec-validate`, `paperspec-load`, `paperspec-stress` and `paperspec-site`, which the pixi tasks and the workflow run.
+- `src/` is Apache-2.0, as `tools/` was.
 - The pixi workspace installs the package editable, and a `dev` environment builds the wheel with `pixi run -e dev wheel`.