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

.gitignore

@@ -0,0 +1,16 @@
+# OS
+.DS_Store
+
+# Go build outputs
+/sojuboy
+/out/
+
+# Local data and env
+/data/
+.env
+
+# Logs
+*.log
+
+# Coverage
+coverage.out