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/.coderabbit.yaml

@@ -0,0 +1,15 @@
+# yaml-language-server: $schema=https://coderabbit.ai/integrations/schema.v2.json
+language: en-US
+reviews:
+  # Skip the vendored SQLite amalgamation. These files are copied verbatim from
+  # upstream SQLite (see the License section in README.md) and are not code that
+  # this project authors or reviews.
+  path_filters:
+    - "!sqlite3-binding.c"
+    - "!sqlite3-binding.h"
+    - "!sqlite3ext.h"
+  auto_review:
+    enabled: true
+    drafts: false
+chat:
+  auto_reply: true