feat: make sims leave rooms when Discord user leaves guild

Listen for GUILD_MEMBER_REMOVE events to remove sim users from
bridged Matrix rooms when their corresponding Discord user leaves
(or is kicked/banned from) the guild. Also removes PluralKit proxy
sims owned by the departing user.

Includes a backfill check on GUILD_CREATE to clean up sims for
users who left while the bridge was offline.

Closes #58

scripts/backfill.js

@@ -10,7 +10,6 @@ if (!channelID) {
 	process.exit(1)
 }
 
-const assert = require("assert/strict")
 const sqlite = require("better-sqlite3")
 const backfill = new sqlite("scripts/backfill.db")
 backfill.prepare("CREATE TABLE IF NOT EXISTS backfill (channel_id TEXT NOT NULL, message_id INTEGER NOT NULL, PRIMARY KEY (channel_id, message_id))").run()
@@ -56,18 +55,8 @@ async function event(event) {
 	if (!channel) return
 	const guild_id = event.d.id
 
-	let roomID = passthrough.select("channel_room", "room_id", {channel_id: channelID}).pluck().get()
-	if (!roomID) {
-		console.log(`Channel #${channel.name} is not bridged yet. Attempting to auto-create...`)
 	try {
-			roomID = await createRoom.syncRoom(channelID)
+		await createRoom.syncRoom(channelID)
-			console.log(`Successfully bridged to new room: ${roomID}`)
-		} catch (e) {
-			console.error(`Failed to auto-create room: ${e.message}`)
-			process.exit(1)
-		}
-	}
-
 		let last = backfill.prepare("SELECT cast(max(message_id) as TEXT) FROM backfill WHERE channel_id = ?").pluck().get(channelID) || "0"
 		console.log(`OK, processing messages for #${channel.name}, continuing from ${last}`)
 
@@ -87,4 +76,8 @@ async function event(event) {
 		}
 
 		process.exit()
+	} catch (e) {
+		console.error(e)
+		process.exit(1) // won't exit automatically on thrown error due to living discord connection, so manual exit is necessary
+	}
 }