Remove Discord and Google OAuth verification from CMS

- Remove Discord + Google OAuth providers from NextAuth config
- Remove social login buttons (Discord/Google) from login form
- Delete link-discord.ts action and discord-verify-form.tsx component
- Simplify verify page to email-only verification flow
- Remove connections settings page and its link from settings
- Clean env.ts, .env, .env.example of Discord/Google client vars
- Remove discordUrl social icon from register, login, and homepage
- Clean translation files: remove continueWithDiscord, continueWithGoogle, connections keys

src/env.ts

@@ -39,11 +39,7 @@ const schema = z.object({
 	AUTH_SECRET: z.string().min(1).optional(),
 	// Laravel APP_KEY (base64:...) — needed to read existing 2FA secrets.
 	APP_KEY: z.string().optional(),
-	// Optional OAuth providers (enabled only when both id+secret are set).
-	DISCORD_CLIENT_ID: z.string().optional(),
-	DISCORD_CLIENT_SECRET: z.string().optional(),
-	GOOGLE_CLIENT_ID: z.string().optional(),
-	GOOGLE_CLIENT_SECRET: z.string().optional(),
+
 	// Mirrors Laravel config('habbo.site.convert_passwords') — enables md5->argon2id.
 	CONVERT_PASSWORDS: z
 		.string()