feat(api): sign-in, refresh rotation and bootstrap admin (M1)

- users, refresh_tokens and audit_log schema (migration 00002)
- argon2id passwords with rehash on login, password policy, lockout
  with exponential back-off and a per-IP rate limit in Redis
- Ed25519 JWT access tokens with kid-based key rotation; rotating
  refresh tokens with reuse detection (cookie for web, body for Android)
- bootstrap admin on first start; must_change_credentials and
  must_change_password gate every other endpoint
- /auth/login, /auth/refresh, /auth/logout(-all), /me, /me/password,
  /me/bootstrap-credentials, /me/sessions; server-info reports
  bootstrap_required
- role policy from docs/auth-and-roles.md with table tests
- problem+json errors with field errors; ru/en translations of the codes
- install.sh and update.sh generate JWT_PRIVATE_KEY

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

services/api/internal/auth/limiter.go

@@ -0,0 +1,41 @@
+package auth
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/redis/go-redis/v9"
+)
+
+// RedisLimiter — счётчик попыток с фиксированным окном в Redis.
+type RedisLimiter struct{ rdb redis.Cmdable }
+
+// NewRedisLimiter создаёт лимитер.
+func NewRedisLimiter(rdb redis.Cmdable) *RedisLimiter { return &RedisLimiter{rdb: rdb} }
+
+// Первый INCR ставит срок окна; ответ — {счётчик, оставшийся TTL в мс}.
+var incrWindow = redis.NewScript(`
+local n = redis.call('INCR', KEYS[1])
+if n == 1 then redis.call('PEXPIRE', KEYS[1], ARGV[1]) end
+return {n, redis.call('PTTL', KEYS[1])}
+`)
+
+// Allow реализует Limiter.
+func (l *RedisLimiter) Allow(ctx context.Context, key string, limit int, window time.Duration) (bool, int, error) {
+	res, err := incrWindow.Run(ctx, l.rdb, []string{"rl:" + key}, window.Milliseconds()).Int64Slice()
+	if err != nil {
+		return false, 0, fmt.Errorf("auth: rate limit: %w", err)
+	}
+	if len(res) != 2 {
+		return false, 0, fmt.Errorf("auth: rate limit: unexpected reply %v", res)
+	}
+	if res[0] <= int64(limit) {
+		return true, 0, nil
+	}
+	retry := int((res[1] + 999) / 1000)
+	if retry < 1 {
+		retry = 1
+	}
+	return false, retry, nil
+}