Revert "Build post chat and attachment workflows"

This reverts commit 0b920da187.

backend/internal/auth/rate_limit.go

@@ -1,68 +0,0 @@
-package auth
-
-import (
-	"strings"
-	"sync"
-	"time"
-)
-
-type LoginRateLimiter struct {
-	mu       sync.Mutex
-	attempts map[string]loginAttempt
-	limit    int
-	window   time.Duration
-}
-
-type loginAttempt struct {
-	Count     int
-	ExpiresAt time.Time
-}
-
-func NewLoginRateLimiter(limit int, window time.Duration) *LoginRateLimiter {
-	return &LoginRateLimiter{
-		attempts: map[string]loginAttempt{},
-		limit:    limit,
-		window:   window,
-	}
-}
-
-func (l *LoginRateLimiter) IsBlocked(key string) bool {
-	l.mu.Lock()
-	defer l.mu.Unlock()
-
-	attempt, ok := l.attempts[key]
-	if !ok || time.Now().After(attempt.ExpiresAt) {
-		delete(l.attempts, key)
-		return false
-	}
-
-	return attempt.Count >= l.limit
-}
-
-func (l *LoginRateLimiter) RecordFailure(key string) {
-	l.mu.Lock()
-	defer l.mu.Unlock()
-
-	now := time.Now()
-	attempt, ok := l.attempts[key]
-	if !ok || now.After(attempt.ExpiresAt) {
-		l.attempts[key] = loginAttempt{
-			Count:     1,
-			ExpiresAt: now.Add(l.window),
-		}
-		return
-	}
-
-	attempt.Count++
-	l.attempts[key] = attempt
-}
-
-func (l *LoginRateLimiter) Clear(key string) {
-	l.mu.Lock()
-	defer l.mu.Unlock()
-	delete(l.attempts, key)
-}
-
-func LoginRateLimitKey(ip string, email string) string {
-	return strings.TrimSpace(ip) + ":" + strings.ToLower(strings.TrimSpace(email))
-}