chore(release): v0.22.0

Full-snapshot bundle (SFM side): document the /db/snapshot,
/db/waveforms/recent.zip and gated /db/restore endpoints. Bump package
version 0.21.1 -> 0.22.0 (pyproject), README version badge + history, and
CHANGELOG. TOOL_VERSION (codec/output provenance) left at 0.21.1 on purpose
— the event codec is unchanged, so existing sidecars must not be flagged
stale for re-backfill.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WyT5m9xppYmoVGmCCVVV6X

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "seismo-relay"
-version = "0.21.1"
+version = "0.22.0"
 description = "Python client and REST server for MiniMate Plus seismographs"
 requires-python = ">=3.10"
 dependencies = [