Add invite links with admin-configurable config creation limits.

Admins can create shareable links that allow redeeming a VPN config a set number of times (or unlimited).

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

db/schema.sql

@@ -72,5 +72,24 @@ CREATE TABLE IF NOT EXISTS tunnel_state (
     data JSONB NOT NULL DEFAULT '{}'::jsonb
 );
 
+CREATE TABLE IF NOT EXISTS invite_links (
+    id UUID PRIMARY KEY,
+    name TEXT NOT NULL DEFAULT '',
+    token TEXT NOT NULL UNIQUE,
+    enabled BOOLEAN NOT NULL DEFAULT TRUE,
+    max_uses INTEGER NOT NULL DEFAULT 1,
+    used_count INTEGER NOT NULL DEFAULT 0,
+    user_id UUID,
+    protocol TEXT NOT NULL DEFAULT 'xui',
+    server_id INTEGER NOT NULL DEFAULT 0,
+    xui_inbound_id INTEGER NOT NULL DEFAULT 0,
+    password_hash TEXT,
+    expires_at TIMESTAMPTZ,
+    note TEXT,
+    created_at TIMESTAMPTZ
+);
+
+CREATE INDEX IF NOT EXISTS idx_invite_links_token ON invite_links(token);
+
 INSERT INTO settings (id, data) VALUES (1, '{}'::jsonb)
 ON CONFLICT (id) DO NOTHING;