feat: initial Beta 1 release

- soju raw connector with event playback and CHATHISTORY fallback
- SQLite store with msgid de-dup and retention job
- Mentions + Pushover + tuning; structured JSON logs
- Summaries: concise, link-following, multi-line grouping
- HTTP: /healthz, /ready, /tail, /trigger, /metrics
- Docker: distroless, healthcheck, version metadata
- Docs: README, CHANGELOG, compose

internal/logging/logging.go

@@ -0,0 +1,24 @@
+package logging
+
+import (
+	"log/slog"
+	"os"
+	"strings"
+)
+
+// New returns a JSON slog logger configured to the provided level string (debug, info, warn, error).
+func New(level string) *slog.Logger {
+	lvl := slog.LevelInfo
+	switch strings.ToLower(strings.TrimSpace(level)) {
+	case "debug":
+		lvl = slog.LevelDebug
+	case "info", "":
+		lvl = slog.LevelInfo
+	case "warn", "warning":
+		lvl = slog.LevelWarn
+	case "err", "error":
+		lvl = slog.LevelError
+	}
+	h := slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{Level: lvl})
+	return slog.New(h)
+}