Initial commit: notifications, monitoring, on-call and incidents

One binary and one SQLite file. Topics with ntfy-style publish and
subscribe, HTTP/TCP/DNS/TLS/heartbeat monitors with a public status page,
schedules and escalation policies, and incidents with a timeline and
post-mortem. The UI follows the Lightwell design language.

Builds against an unreleased Reef (secretbox) through a local replace line.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

go.mod

@@ -0,0 +1,24 @@
+module git.veillax.com/Veillax/sandbar
+
+go 1.27.3
+
+require (
+	git.veillax.com/Veillax/reef v0.1.7
+	golang.org/x/crypto v0.58.0
+	modernc.org/sqlite v1.61.0
+)
+
+require (
+	github.com/dustin/go-humanize v1.1.0 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/mattn/go-isatty v0.0.24 // indirect
+	github.com/ncruces/go-strftime v1.1.0 // indirect
+	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
+	golang.org/x/sys v0.49.0 // indirect
+	modernc.org/libc v1.79.0 // indirect
+	modernc.org/mathutil v1.7.1 // indirect
+	modernc.org/memory v1.12.1 // indirect
+)
+
+// Local development against an unreleased Reef (it gains secretbox). Remove once Reef is tagged.
+replace git.veillax.com/Veillax/reef => ../reef