Add IP autoban system: banned_ips table, global ipGuard middleware, 24h bans on honeypot fill / 10 failed logins / 10 wrong share passwords; trust proxy for real client IPs behind funnel; admin API and settings UI to manage active bans

db/migration.sql

@@ -4,6 +4,13 @@ CREATE TABLE IF NOT EXISTS students (
   created_at TIMESTAMPTZ DEFAULT now()
 );
 
+CREATE TABLE IF NOT EXISTS banned_ips (
+  ip VARCHAR(64) PRIMARY KEY,
+  reason VARCHAR(100) NOT NULL,
+  banned_until TIMESTAMPTZ NOT NULL,
+  created_at TIMESTAMPTZ DEFAULT now()
+);
+
 ALTER TABLE students ADD COLUMN IF NOT EXISTS group_id INT REFERENCES groups(id);
 
 CREATE TABLE IF NOT EXISTS settings (