feat: record backup snapshots during run completion

Upsert SnapshotRecord rows directly from run_pobsync_backup results so
new successful and failed backup runs are reflected in the database
without requiring a separate discovery pass. Keep discovery for existing
snapshots and repair workflows, and cover success, failure, and dry-run
behavior with tests.

src/pobsync_backend/snapshot_discovery.py

@@ -45,19 +45,10 @@ def discover_snapshots(
         host_root = resolve_host_root(global_config.backup_root, host_config.host)
         for kind in kinds:
             for snapshot_dir in iter_snapshot_dirs(host_root, kind):
-                meta = read_snapshot_meta(snapshot_dir)
-                defaults = {
-                    "path": str(snapshot_dir),
-                    "status": str(meta.get("status") or ""),
-                    "started_at": parse_snapshot_datetime(snapshot_dir.name, meta, "started_at"),
-                    "ended_at": parse_snapshot_datetime(snapshot_dir.name, meta, "ended_at"),
-                    "metadata": meta,
-                }
-                _record, was_created = SnapshotRecord.objects.update_or_create(
+                _record, was_created = upsert_snapshot_record(
                     host=host_config,
                     kind=kind,
-                    dirname=snapshot_dir.name,
-                    defaults=defaults,
+                    snapshot_dir=snapshot_dir,
                 )
                 scanned += 1
                 if was_created:
@@ -73,6 +64,34 @@ def discover_snapshots(
     }
 
 
+def upsert_snapshot_record(*, host: HostConfig, kind: str, snapshot_dir: Path) -> tuple[SnapshotRecord, bool]:
+    meta = read_snapshot_meta(snapshot_dir)
+    defaults = {
+        "path": str(snapshot_dir),
+        "status": str(meta.get("status") or ""),
+        "started_at": parse_snapshot_datetime(snapshot_dir.name, meta, "started_at"),
+        "ended_at": parse_snapshot_datetime(snapshot_dir.name, meta, "ended_at"),
+        "metadata": meta,
+    }
+    return SnapshotRecord.objects.update_or_create(
+        host=host,
+        kind=kind,
+        dirname=snapshot_dir.name,
+        defaults=defaults,
+    )
+
+
+def infer_snapshot_kind(snapshot_path: Path) -> str:
+    parent = snapshot_path.parent.name
+    if parent == "scheduled":
+        return "scheduled"
+    if parent == "manual":
+        return "manual"
+    if parent == ".incomplete":
+        return "incomplete"
+    raise ValueError(f"Cannot infer snapshot kind from path: {snapshot_path}")
+
+
 def _parse_iso_z(value: str) -> datetime | None:
     try:
         if value.endswith("Z"):