feat(scripts): add config migration script for guild settings

Add script to migrate existing config.json values to database with
bun run db:migrate-config command.

shared/scripts/migrate-config-to-db.ts

@@ -0,0 +1,51 @@
+import { guildSettingsService } from "@shared/modules/guild-settings/guild-settings.service";
+import { config } from "@shared/lib/config";
+import { env } from "@shared/lib/env";
+
+async function migrateConfigToDatabase() {
+    const guildId = env.DISCORD_GUILD_ID;
+
+    if (!guildId) {
+        console.error("DISCORD_GUILD_ID not set. Cannot migrate config.");
+        console.log("Set DISCORD_GUILD_ID in your environment to migrate config.");
+        process.exit(1);
+    }
+
+    console.log(`Migrating config for guild ${guildId}...`);
+
+    const existing = await guildSettingsService.getSettings(guildId);
+    if (existing) {
+        console.log("Guild settings already exist in database:");
+        console.log(JSON.stringify(existing, null, 2));
+        console.log("\nSkipping migration. Delete existing settings first if you want to re-migrate.");
+        return;
+    }
+
+    await guildSettingsService.upsertSettings({
+        guildId,
+        studentRoleId: config.studentRole ?? undefined,
+        visitorRoleId: config.visitorRole ?? undefined,
+        colorRoleIds: config.colorRoles ?? [],
+        welcomeChannelId: config.welcomeChannelId ?? undefined,
+        welcomeMessage: config.welcomeMessage ?? undefined,
+        feedbackChannelId: config.feedbackChannelId ?? undefined,
+        terminalChannelId: config.terminal?.channelId ?? undefined,
+        terminalMessageId: config.terminal?.messageId ?? undefined,
+        moderationLogChannelId: config.moderation?.cases?.logChannelId ?? undefined,
+        moderationDmOnWarn: config.moderation?.cases?.dmOnWarn ?? true,
+        moderationAutoTimeoutThreshold: config.moderation?.cases?.autoTimeoutThreshold ?? undefined,
+    });
+
+    console.log("✅ Migration complete!");
+    console.log("\nGuild settings are now stored in the database.");
+    console.log("You can manage them via:");
+    console.log("  - /settings command in Discord");
+    console.log("  - API endpoints at /api/guilds/:guildId/settings");
+}
+
+migrateConfigToDatabase()
+    .then(() => process.exit(0))
+    .catch((error) => {
+        console.error("Migration failed:", error);
+        process.exit(1);
+    });