Update admin panel and server configuration

schema.sql

@@ -68,6 +68,17 @@ CREATE TABLE IF NOT EXISTS feed_requests (
   admin_notes TEXT
 );
 
+-- Environment variable settings stored in database
+CREATE TABLE IF NOT EXISTS settings (
+  key TEXT PRIMARY KEY,
+  value TEXT,
+  is_credential BOOLEAN DEFAULT 0,
+  description TEXT,
+  default_value TEXT,
+  required BOOLEAN DEFAULT 0,
+  updated_at TEXT NOT NULL
+);
+
 -- Create indexes for better performance
 CREATE INDEX IF NOT EXISTS idx_articles_feed_id ON articles(feed_id);
 CREATE INDEX IF NOT EXISTS idx_articles_pub_date ON articles(pub_date);
@@ -78,3 +89,4 @@ CREATE INDEX IF NOT EXISTS idx_tts_queue_status ON tts_queue(status);
 CREATE INDEX IF NOT EXISTS idx_tts_queue_created_at ON tts_queue(created_at);
 CREATE INDEX IF NOT EXISTS idx_feed_requests_status ON feed_requests(status);
 CREATE INDEX IF NOT EXISTS idx_feed_requests_created_at ON feed_requests(created_at);
+CREATE INDEX IF NOT EXISTS idx_settings_is_credential ON settings(is_credential);