Add initial Go CLI skeleton

internal/db/schema/003_events.sql

@@ -0,0 +1,18 @@
+CREATE TABLE IF NOT EXISTS events (
+  event_id INTEGER PRIMARY KEY AUTOINCREMENT,
+  run_id TEXT NOT NULL,
+  task_id TEXT NOT NULL,
+  thread_id TEXT,
+  source TEXT NOT NULL,
+  event_type TEXT NOT NULL,
+  message_id TEXT,
+  summary TEXT NOT NULL DEFAULT '',
+  payload_json TEXT NOT NULL DEFAULT '{}',
+  created_at TEXT NOT NULL
+);
+
+CREATE INDEX IF NOT EXISTS idx_events_run_event
+  ON events(run_id, event_id);
+
+CREATE INDEX IF NOT EXISTS idx_events_thread_event
+  ON events(thread_id, event_id);