feat(store): миграция sessions/password + методы users/sessions/projects

Фаза 2, Task 1: добавлена таблица sessions и nullable password_hash у
users, sqlc-запросы и *Store-обёртки (CreateUser, GetUserByEmail,
CreateProjectForUser, GetProjectOwned, GetUserProject, CreateSession,
GetSessionUser, DeleteSession, RegisterUser в транзакции), интеграционные
тесты на testcontainers.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BwxdSt4reTm7Dj1oxRvpP3

internal/store/db/models.go

@@ -43,6 +43,14 @@ type ProviderAccount struct {
 	CreatedAt pgtype.Timestamptz `json:"created_at"`
 }
 
+type Session struct {
+	ID        uuid.UUID          `json:"id"`
+	UserID    uuid.UUID          `json:"user_id"`
+	TokenHash string             `json:"token_hash"`
+	ExpiresAt pgtype.Timestamptz `json:"expires_at"`
+	CreatedAt pgtype.Timestamptz `json:"created_at"`
+}
+
 type Template struct {
 	ID        uuid.UUID          `json:"id"`
 	ProjectID uuid.UUID          `json:"project_id"`
@@ -54,7 +62,8 @@ type Template struct {
 }
 
 type User struct {
-	ID        uuid.UUID          `json:"id"`
-	Email     string             `json:"email"`
-	CreatedAt pgtype.Timestamptz `json:"created_at"`
+	ID           uuid.UUID          `json:"id"`
+	Email        string             `json:"email"`
+	CreatedAt    pgtype.Timestamptz `json:"created_at"`
+	PasswordHash *string            `json:"password_hash"`
 }