(release) Prepare 1.0.0 release metadata

Add the initial 1.0.0 changelog, bump the package/application version,
and expose the release version through `pobsync --version`.

Cover the version output in the console entrypoint tests.

src/pobsync/__init__.py

@@ -1,3 +1,2 @@
 __all__ = ["__version__"]
-__version__ = "0.1.0"
-
+__version__ = "1.0.0"

src/pobsync/cli.py

@@ -6,6 +6,8 @@ from typing import Sequence
 
 from django.core.management import execute_from_command_line
 
+from pobsync import __version__
+
 
 COMMAND_ALIASES = {
     "backup": "run_pobsync_backup",
@@ -34,6 +36,9 @@ Configuration is managed from the Django control panel. Use
 
 def main(argv: Sequence[str] | None = None) -> int:
     args = list(sys.argv[1:] if argv is None else argv)
+    if args and args[0] in {"--version", "version"}:
+        print(f"pobsync {__version__}")
+        return 0
     if not args or args[0] in {"-h", "--help", "help"}:
         print(_usage())
         return 0

src/pobsync_backend/tests/test_console_entrypoint.py

@@ -9,6 +9,14 @@ from pobsync.cli import main
 
 
 class ConsoleEntrypointTests(SimpleTestCase):
+    def test_version_prints_package_version(self) -> None:
+        stdout = StringIO()
+        with patch("sys.stdout", stdout):
+            exit_code = main(["--version"])
+
+        self.assertEqual(exit_code, 0)
+        self.assertEqual(stdout.getvalue().strip(), "pobsync 1.0.0")
+
     def test_maps_backup_alias_to_django_command(self) -> None:
         with patch("pobsync.cli.execute_from_command_line") as execute:
             exit_code = main(["backup", "web-01", "--dry-run"])