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>

tools/load.py

@@ -1,82 +0,0 @@
-#!/usr/bin/env python3
-"""Load packages into a SQLite database with the tables of sql/doc.sql and sql/store.sql.
-
-Non-normative tooling.
-Usage: python3 tools/load.py --sqlite lab.db PACKAGE [PACKAGE ...]
-       python3 tools/load.py --sqlite lab.db --bundle --built-from REV PACKAGE [PACKAGE ...]
-A package is a folder, or a zipped package (`.sct.zip`), unpacked under the rules of spec/12 §12.2 first.
-With --bundle the new file is a scienting-bundle/1: it also gets the tables of sql/bundle-sqlite.sql,
-the full-text search index and bundle_meta (spec/13 §13.5).
-Each package is validated first, and nothing is loaded if any package fails.
-Files without tables of their own (assets, datasets, derived files) are copied by SHA-256 into an
-asset store folder beside the database, named <database>.assets/.
-"""
-
-import argparse
-import os
-import sqlite3
-import sys
-import tempfile
-
-ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
-sys.path.insert(0, ROOT)
-import tools  # noqa: E402,F401  checks the runtime and puts src/ first on the path, before paperspec is imported
-
-from paperspec import db, package  # noqa: E402
-from paperspec.schema import Store  # noqa: E402
-
-
-def main():
-    ap = argparse.ArgumentParser(description=__doc__.splitlines()[0])
-    ap.add_argument("--sqlite", required=True, help="the database file; created with the tables if new")
-    ap.add_argument("--bundle", action="store_true", help="build a new scienting-bundle/1 file with search")
-    ap.add_argument("--built-from", help="with --bundle: the store revision the packages come from")
-    ap.add_argument("--store", help="with --bundle: the store's name (default: the packages' common store)")
-    ap.add_argument("--max-size", metavar="BYTES", type=int, default=package.ZIP_LIMIT,
-                    help="refuse a zipped package that expands past this many bytes (default %d)" % package.ZIP_LIMIT)
-    ap.add_argument("packages", nargs="+", help="package folders or zipped packages")
-    a = ap.parse_args()
-    if a.bundle and (os.path.exists(a.sqlite) or not a.built_from):
-        ap.error("--bundle needs --built-from and a database file that does not exist yet")
-    store, bad = Store(os.path.join(ROOT, "schemas")), False
-    with tempfile.TemporaryDirectory() as tmp:
-        folders = []
-        for i, p in enumerate(a.packages):
-            if package.is_zip(p):
-                try:
-                    folders.append(package.read_zip(p, os.path.join(tmp, str(i)), a.max_size))
-                except package.Refusal as e:
-                    print("%s: %s: %s" % (p, e.rule, e.message), file=sys.stderr)
-                    bad = True
-                    continue
-            else:
-                folders.append(p)
-            for e in package.validate(folders[-1], store).errors:
-                print("%s: %s: %s: %s" % (p, e["where"], e["rule"], e["message"]), file=sys.stderr)
-                bad = True
-        if bad:
-            sys.exit("Nothing was loaded.")
-        new = not os.path.exists(a.sqlite)
-        conn = sqlite3.connect(a.sqlite)
-        if a.bundle:
-            db.create_bundle(conn, os.path.join(ROOT, "sql"))
-        elif new:
-            db.create(conn, os.path.join(ROOT, "sql"))
-        for p in folders:
-            key = db.load(conn, p, a.sqlite + ".assets")
-            n = conn.execute("SELECT COUNT(*) FROM nodes WHERE doc_key = ?", (key,)).fetchone()[0]
-            if a.bundle:
-                print("%s: %d nodes, %d search rows" % (key, n, db.index(conn, key)))
-            else:
-                print("%s: %d nodes" % (key, n))
-        if a.bundle:
-            stores = {r[0] for r in conn.execute("SELECT DISTINCT store FROM documents WHERE store IS NOT NULL")}
-            store_name = a.store or (stores.pop() if len(stores) == 1 else None)
-            if store_name is None:
-                sys.exit("The packages name no single store; give one with --store.")
-            db.write_meta(conn, store_name, a.built_from)
-        conn.commit()
-
-
-if __name__ == "__main__":
-    main()