⭐feat: Add Steam account linking with team creation (#274)

## Description
<!-- Briefly describe the purpose and scope of your changes -->


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

- **New Features**
- Introduced a real-time Steam login flow using QR codes and server-sent
events (SSE) for team creation and authentication.
- Added Steam account and friend management, including secure credential
storage and friend list synchronization.
- Integrated Steam login endpoints into the API, enabling QR code-based
login and automated team setup.

- **Improvements**
- Enhanced data security by implementing encrypted storage for sensitive
tokens.
- Updated database schema to support Steam accounts, teams, memberships,
and social connections.
- Refined type definitions and consolidated account-related information
for improved consistency.

- **Bug Fixes**
  - Fixed trade ban status representation for Steam accounts.

- **Chores**
- Removed legacy C# Steam authentication service and related
configuration files.
  - Updated and cleaned up package dependencies and development tooling.
  - Streamlined type declaration files and resource definitions.

- **Style**
- Redesigned the team creation page UI with a modern, animated QR code
login interface.

- **Documentation**
  - Updated OpenAPI documentation for new Steam login endpoints.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/core/src/utils/token.ts

@@ -0,0 +1,58 @@
+import { z } from 'zod';
+import { fn } from './fn';
+import crypto from 'crypto';
+import { Resource } from 'sst';
+
+// This is a 32-character random ASCII string
+const rawKey = Resource.SteamEncryptionKey.value;
+
+// Turn it into exactly 32 bytes via UTF-8
+const key = Buffer.from(rawKey, 'utf8');
+if (key.length !== 32) {
+    throw new Error(
+        `SteamEncryptionKey must be exactly 32 bytes; got ${key.length}`
+    );
+}
+
+const ENCRYPTION_IV_LENGTH = 12; // 96 bits for GCM
+
+export namespace Token {
+    export const encrypt = fn(
+        z.string().min(4),
+        (token) => {
+            const iv = crypto.randomBytes(ENCRYPTION_IV_LENGTH);
+            const cipher = crypto.createCipheriv('aes-256-gcm', key, iv);
+
+            const ciphertext = Buffer.concat([
+                cipher.update(token, 'utf8'),
+                cipher.final(),
+            ]);
+            const tag = cipher.getAuthTag();
+
+            return ['v1', iv.toString('hex'), tag.toString('hex'), ciphertext.toString('hex')].join(':');
+        });
+
+    export const decrypt = fn(
+        z.string().min(4),
+        (data) => {
+            const [version, ivHex, tagHex, ciphertextHex] = data.split(':');
+            if (version !== 'v1' || !ivHex || !tagHex || !ciphertextHex) {
+                throw new Error('Invalid token format');
+            }
+
+            const iv = Buffer.from(ivHex, 'hex');
+            const tag = Buffer.from(tagHex, 'hex');
+            const ciphertext = Buffer.from(ciphertextHex, 'hex');
+
+            const decipher = crypto.createDecipheriv('aes-256-gcm', key, iv);
+            decipher.setAuthTag(tag);
+
+            const plaintext = Buffer.concat([
+                decipher.update(ciphertext),
+                decipher.final(),
+            ]);
+
+            return plaintext.toString('utf8');
+        });
+        
+}