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/summarizer/summarizer.go

@@ -0,0 +1,14 @@
+package summarizer
+
+import (
+    "context"
+    "time"
+
+    "sojuboy/internal/store"
+)
+
+type Summarizer interface {
+    Summarize(ctx context.Context, channel string, msgs []store.Message, window time.Duration) (string, error)
+}
+
+