(release) Prepare 1.2.0

Bump the package version to 1.2.0 and document the operations-focused release
with updater, readonly access, notifications, bandwidth controls, live progress,
and more robust retention cleanup.

Make the CLI version test assert against the package version so future release
bumps do not require changing a hardcoded expected value.

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "pobsync"
-version = "1.1.0"
+version = "1.2.0"
 description = "Pull-based rsync backup tool with hardlinked snapshots"
 requires-python = ">=3.11"
 dependencies = [