feat: Add SSH public key storage for users

- Add ssh_public_key column to User model for storing SSH keys
- Add database migration for ssh_public_key column
- Add SSH key section in user profile settings with validation
- Auto-inject user's SSH key when deploying VMs from templates
- Auto-inject user's SSH key when creating LXC containers
- Support for both regular and smart LXC creation endpoints
- Add i18n translations for SSH key UI (ru/en)
- Validate SSH key format (ssh-rsa, ssh-ed25519, ecdsa-sha2, ssh-dss)

Users can now save their SSH public key in Settings -> Account,
and it will be automatically added to any VM or LXC container
they create, enabling passwordless SSH access.

backend/migrations/migrations.py

@@ -875,6 +875,22 @@ def migrate_snapshot_archives(conn):
     logger.info("✓ Snapshot archives table created")
 
 
+# ==================== Migration 12: User SSH Public Key ====================
+
+def migrate_user_ssh_key(conn):
+    """Add SSH public key column to users table"""
+    
+    if column_exists(conn, 'users', 'ssh_public_key'):
+        logger.info("✓ User SSH public key column already exists")
+        return
+    
+    logger.info("Adding SSH public key column to users table...")
+    
+    add_column_if_not_exists(conn, 'users', 'ssh_public_key', 'TEXT')
+    
+    logger.info("✓ User SSH public key column added")
+
+
 # ==================== Main Migration Function ====================
 
 def run_all_migrations(engine, db_session=None):
@@ -978,6 +994,14 @@ def run_all_migrations(engine, db_session=None):
             except Exception as e:
                 logger.warning(f"Snapshot archives migration: {e}")
                 conn.rollback()
+            
+            # Migration 12: User SSH Public Key
+            try:
+                migrate_user_ssh_key(conn)
+                conn.commit()
+            except Exception as e:
+                logger.warning(f"User SSH key migration: {e}")
+                conn.rollback()
         
         logger.info("=" * 50)
         logger.info("✓ All migrations completed successfully")