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

CHANGELOG.md

@@ -8,6 +8,40 @@ All notable changes to seismo-relay are documented here.
 
 ---
 
+## v0.22.0 — 2026-07-03
+
+Full-snapshot bundle support (SFM side).  Adds the DB-snapshot, recent-waveform,
+and gated-restore endpoints Terra-View drives to pull a complete prod→dev refresh
+— the `seismo_relay.db` plus the waveform files behind recent events — in one
+pass.  Pairs with **Terra-View v0.17.0**'s "Create full snapshot (incl. SFM)"
+control on Settings → Database.  New logic lives in `sfm/db_snapshot.py`, kept
+out of `server.py` so it's unit-testable without HTTP.
+
+### Added
+
+- **`GET /db/snapshot`** — streams a WAL-safe point-in-time copy of
+  `seismo_relay.db`, taken through the SQLite online backup API (not a raw
+  file grab), so the download stays consistent even while the ACH server is
+  writing under WAL.
+- **`GET /db/waveforms/recent.zip?n=…`** — zips the on-disk files (event file
+  + its `.h5` / sidecar siblings) for the *n* most-recent events, arcname
+  `<serial>/<filename>`, so a dev box can restore chart-openable events without
+  hauling the entire waveform store.  Events with no resolvable files on disk
+  are skipped.
+- **`POST /db/restore`** — gated by `SFM_DB_RESTORE_ENABLED` (dormant → 404
+  unless explicitly enabled; dev-only).  Validates the uploaded DB first, takes
+  a WAL-safe `.pre-restore-<ts>` safety backup of the current DB, then swaps in
+  the restored DB + waveforms.  Zip entries are path-traversal-guarded before
+  extraction.
+
+### Fixed
+
+- **Restore no longer blocks the event loop.**  `/db/restore` runs its
+  synchronous DB/file work in a threadpool instead of `async def`, so a large
+  restore can't stall inbound ACH connections or other API requests.
+
+---
+
 ## v0.21.1 — 2026-06-01
 
 Bug fixes against v0.21.0 surfaced after the first prod redeploy.  Three