Derive the version from git with verri

Use verri's strawberry flavour through hatchling's code version source, so
versions look like 2026.10.21.0: the HEAD commit date plus the number of
earlier commits that day.

Container images build the sdist in a separate stage that has the git
repository, so they get the same version instead of a +vcs.missing one.

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

peo/__init__.py

@@ -2,4 +2,6 @@
 # SPDX-License-Identifier: GPL-3.0-or-later
 """peo: serves neo4j-browser and translates Bolt/Cypher to PostgreSQL + AGE."""
 
-__version__ = "0.1.0"
+from importlib.metadata import version
+
+__version__ = version("peo")