feat(v2): T-309 SQLite fall-event persistence (mattn/go-sqlite3)

Persist confirmed fall events to a local SQLite DB under artifacts/:
camera host/port/channel + event id/track/source/config version/state/
latency/screenshot path/confirmed-at. Schema stores no password (guarded
by test). Wire openRecorder/saveRecord into the alerts loop; failures are
non-fatal. Re-applied the SILVER-POSE vendored os_windows.go patch that
go mod vendor reverted.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

v2/vendor/github.com/mattn/go-sqlite3/sqlite3_libsqlite3.go

@@ -0,0 +1,23 @@
+// Copyright (C) 2019 Yasuhiro Matsumoto <mattn.jp@gmail.com>.
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file.
+
+//go:build libsqlite3
+// +build libsqlite3
+
+package sqlite3
+
+/*
+#cgo CFLAGS: -DUSE_LIBSQLITE3
+#cgo linux LDFLAGS: -lsqlite3
+#cgo darwin,amd64 LDFLAGS: -L/usr/local/opt/sqlite/lib -lsqlite3
+#cgo darwin,amd64 CFLAGS:  -I/usr/local/opt/sqlite/include
+#cgo darwin,arm64 LDFLAGS: -L/opt/homebrew/opt/sqlite/lib -lsqlite3
+#cgo darwin,arm64 CFLAGS:  -I/opt/homebrew/opt/sqlite/include
+#cgo openbsd LDFLAGS: -lsqlite3
+#cgo solaris LDFLAGS: -lsqlite3
+#cgo windows LDFLAGS: -lsqlite3
+#cgo zos LDFLAGS: -lsqlite3
+*/
+import "C"