feat: Implement secure email/password authentication with user registration, API rate limiting, and dynamic homepage navigation.

prisma/migrations/rate_limit.sql

@@ -0,0 +1,31 @@
+-- Rate Limiting Table (UNLOGGED for performance)
+-- Run this migration manually: psql $DATABASE_URL -f prisma/migrations/rate_limit.sql
+
+-- Drop if exists (for re-running)
+DROP TABLE IF EXISTS rate_limits;
+
+-- Create UNLOGGED table for rate limiting
+-- UNLOGGED = no WAL writes = faster, but data lost on crash (acceptable for rate limits)
+CREATE UNLOGGED TABLE rate_limits (
+    id SERIAL PRIMARY KEY,
+    key VARCHAR(255) NOT NULL,           -- e.g., "register:192.168.1.1" or "login:[email protected]"
+    action VARCHAR(50) NOT NULL,          -- e.g., "register", "login", "api"
+    count INTEGER NOT NULL DEFAULT 1,
+    window_start TIMESTAMP NOT NULL DEFAULT NOW(),
+    
+    -- Unique constraint for upsert operations
+    UNIQUE(key, action)
+);
+
+-- Index for fast lookups
+CREATE INDEX idx_rate_limits_key_action ON rate_limits(key, action);
+
+-- Index for cleanup operations
+CREATE INDEX idx_rate_limits_window_start ON rate_limits(window_start);
+
+-- Auto-cleanup function: removes expired entries
+CREATE OR REPLACE FUNCTION cleanup_rate_limits() RETURNS void AS $$
+BEGIN
+    DELETE FROM rate_limits WHERE window_start < NOW() - INTERVAL '1 hour';
+END;
+$$ LANGUAGE plpgsql;