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/go.sum

@@ -9,6 +9,8 @@ github.com/go-text/typesetting v0.3.4 h1:YYurUOtEb9kGSOz4uE3k4OpBGsp1dDL8+fjCeaF
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 github.com/go-text/typesetting-utils v0.0.0-20260223113751-2d88ac90dae3/go.mod h1:3/62I4La/HBRX9TcTpBj4eipLiwzf+vhI+7whTc9V7o=
+github.com/mattn/go-sqlite3 v1.14.48 h1:7XHIgl0a8HwOaiK4E47ozLkST78rR9+OtNGx27D/TFs=
+github.com/mattn/go-sqlite3 v1.14.48/go.mod h1:6JTjA44L93a0QCyJef5YvlPoKXntQPjzWv5gtm9sB6w=
 github.com/yalue/onnxruntime_go v1.12.1 h1:joCCmBnNjHy04jK9EMP/UV6oPPqySXlRgf3gcUcnI/g=
 github.com/yalue/onnxruntime_go v1.12.1/go.mod h1:b4X26A8pekNb1ACJ58wAXgNKeUCGEAQ9dmACut9Sm/4=
 golang.org/x/exp v0.0.0-20250408133849-7e4ce0ab07d0 h1:R84qjqJb5nVJMxqWYb3np9L5ZsaDtB+a39EqjV0JSUM=