Issue invite configs as subscription URLs with redeem-based lifetime.

Admin picks inbound once, sets duration in days from Get config, and configures the 3x-ui /sub base URL.

Co-authored-by: Cursor <cursoragent@cursor.com>

db/connection.py

@@ -84,6 +84,9 @@ def init_schema():
             cur.execute(
                 "CREATE INDEX IF NOT EXISTS idx_users_xui_email ON users(xui_email)"
             )
+            cur.execute(
+                "ALTER TABLE invite_links ADD COLUMN IF NOT EXISTS duration_days INTEGER NOT NULL DEFAULT 0"
+            )
         conn.commit()
     _schema_ready = True
     logger.info('PostgreSQL schema ready')