feat: Add db voice session tracking

data/schema.sql

@@ -10,4 +10,15 @@ CREATE TABLE voicelog_guilds(
 CREATE TRIGGER voicelog_guilds_timestamp BEFORE UPDATE ON voicelog_guilds 
   FOR EACH ROW EXECUTE FUNCTION update_timestamp_column();
 
+CREATE TABLE voicelog_sessions(
+  sessionid INTEGER GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
+  guildid BIGINT NOT NULL REFERENCES voicelog_guilds (guildid) ON DELETE CASCADE ON UPDATE CASCADE,
+  userid BIGINT NOT NULL,
+  channelid BIGINT NOT NULL,
+  joined_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+  duration INTEGER
+);
+
+CREATE INDEX voicelog_sessions_guildid_userid ON voicelog_sessions (guildid, userid);
+
 COMMIT;