Feature user and admin panels (#30)

migrations/003_global_settings.sql

@@ -0,0 +1,15 @@
+-- Migration 003: Global Settings
+-- Stores application-wide configuration managed by admins.
+
+CREATE TABLE IF NOT EXISTS global_settings (
+    key VARCHAR(100) PRIMARY KEY,
+    value JSONB NOT NULL DEFAULT '{}'::jsonb,
+    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    updated_by UUID REFERENCES users(id)
+);
+
+-- Seed defaults
+INSERT INTO global_settings (key, value) VALUES
+    ('registration', '{"enabled": true}'::jsonb),
+    ('site', '{"name": "Chat Switchboard", "tagline": "Multi-Model AI Chat"}'::jsonb)
+ON CONFLICT (key) DO NOTHING;