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/SECURITY.md

@@ -0,0 +1,33 @@
+# Security Policy
+
+## Supported Versions
+
+Only the latest release on the `v1.14.x` line receives security fixes.
+
+| Version  | Supported          |
+| -------- | ------------------ |
+| 1.14.x   | :white_check_mark: |
+| < 1.14   | :x:                |
+
+## Scope
+
+`go-sqlite3` is a CGo binding that bundles the SQLite amalgamation
+(`sqlite3-binding.c` / `sqlite3-binding.h`). Please report issues to the
+appropriate project:
+
+- Bugs in the Go binding layer, CGo glue, build tags, or this repository's
+  own code: report here.
+- Vulnerabilities in SQLite itself: please report them upstream to the
+  SQLite developers at <https://www.sqlite.org/>. Once a fix is released
+  upstream, this repository will update the bundled amalgamation.
+
+## Reporting a Vulnerability
+
+Please **do not** open a public GitHub issue for security problems.
+
+Use GitHub's private vulnerability reporting:
+<https://github.com/mattn/go-sqlite3/security/advisories/new>
+
+This project is maintained on a best-effort basis by volunteers, so please
+allow reasonable time for investigation and a fix before any public
+d