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/cmd/api/main.go

@@ -3,13 +3,17 @@ package main
 
 import (
 	"context"
+	"crypto/ed25519"
+	"fmt"
 	"log/slog"
 	"os"
 	"os/signal"
 	"syscall"
 
+	"github.com/jackc/pgx/v5/pgxpool"
 	"github.com/redis/go-redis/v9"
 
+	"pipu/api/internal/auth"
 	"pipu/api/internal/buildinfo"
 	"pipu/api/internal/platform/config"
 	"pipu/api/internal/platform/db"
@@ -56,16 +60,69 @@ func run() error {
 	rdb := redis.NewClient(redisOpts)
 	defer func() { _ = rdb.Close() }()
 
+	authSvc, err := newAuthService(cfg, pool, rdb, log)
+	if err != nil {
+		return err
+	}
+	if err := authSvc.Bootstrap(ctx); err != nil {
+		return err
+	}
+
 	sys := system.NewHandler(system.Info{
 		Version:               buildinfo.Version,
 		SupportedLocales:      cfg.SupportedLocales,
 		MinAndroidVersionCode: cfg.MinAndroidVersionCode,
+		BootstrapRequired:     authSvc.BootstrapRequired,
 	}, log, map[string]system.Checker{
 		"postgres": system.CheckerFunc(pool.Ping),
 		"redis":    system.CheckerFunc(func(ctx context.Context) error { return rdb.Ping(ctx).Err() }),
 	})
 
-	srv := httpx.NewServer(cfg.HTTPAddr, server.NewRouter(server.Deps{Log: log, System: sys}))
+	srv := httpx.NewServer(cfg.HTTPAddr, server.NewRouter(server.Deps{
+		Log:         log,
+		System:      sys,
+		Auth:        auth.NewHandler(authSvc, cfg.CookieSecure),
+		AuthService: authSvc,
+	}))
 	log.Info("starting", "version", buildinfo.Version)
 	return httpx.Serve(ctx, log, srv, cfg.ShutdownTimeout)
 }
+
+func newAuthService(cfg config.API, pool *pgxpool.Pool, rdb *redis.Client, log *slog.Logger) (*auth.Service, error) {
+	var (
+		key ed25519.PrivateKey
+		err error
+	)
+	if cfg.JWTPrivateKey == "" {
+		log.Warn("JWT_PRIVATE_KEY is not set: using a random key, access tokens will not survive a restart")
+		key, err = auth.GenerateKey()
+	} else {
+		key, err = auth.ParsePrivateKey(cfg.JWTPrivateKey)
+	}
+	if err != nil {
+		return nil, err
+	}
+	var previous []ed25519.PrivateKey
+	for _, s := range cfg.JWTPreviousKeys {
+		if s == "" {
+			continue
+		}
+		k, err := auth.ParsePrivateKey(s)
+		if err != nil {
+			return nil, fmt.Errorf("JWT_PREVIOUS_KEYS: %w", err)
+		}
+		previous = append(previous, k)
+	}
+	clock := auth.SystemClock{}
+	acfg := auth.DefaultConfig()
+	acfg.BootstrapUsername = cfg.BootstrapAdminUsername
+	acfg.BootstrapPassword = cfg.BootstrapAdminPassword
+	acfg.SupportedLocales = cfg.SupportedLocales
+	return auth.NewService(
+		auth.NewPgStore(pool),
+		auth.NewHasher(auth.DefaultArgon2Params),
+		auth.NewTokenIssuer(key, previous, cfg.AccessTokenTTL, clock.Now),
+		auth.NewRedisLimiter(rdb),
+		clock, auth.UUIDv7{}, log, acfg,
+	)
+}