refactor: Gitea 式目录改组，移除本分支 SPA 与杂项产物

将 model/service/handler/middleware 迁至 models/services/routers/api/modules/auth，并删除 frontend、embed_static、scripts 及误入库缓存/二进制。

Co-authored-by: Cursor <cursoragent@cursor.com>

models/oauth.go

@@ -0,0 +1,31 @@
+package model
+
+import "time"
+
+// OAuthClient OIDC/OAuth2 客户端应用（密钥仅存 bcrypt 哈希）
+type OAuthClient struct {
+	ID               uint      `gorm:"primaryKey" json:"id"`
+	ClientID         string    `gorm:"uniqueIndex;size:128;not null" json:"client_id"`
+	ClientSecretHash string    `gorm:"size:128;not null" json:"-"`
+	Name             string    `gorm:"size:128;not null" json:"name"`
+	RedirectURIs     string    `gorm:"size:2048;not null" json:"redirect_uris"`
+	Enabled          bool      `gorm:"default:true" json:"enabled"`
+	CreatedAt        time.Time `json:"created_at"`
+	UpdatedAt        time.Time `json:"updated_at"`
+}
+
+// OAuthAuthCode 一次性授权码（OIDC Authorization Code Flow）
+type OAuthAuthCode struct {
+	ID                  uint      `gorm:"primaryKey"`
+	Code                string    `gorm:"uniqueIndex;size:64;not null"`
+	ClientID            string    `gorm:"size:128;not null;index"`
+	UserID              uint      `gorm:"not null;index"`
+	RedirectURI         string    `gorm:"size:512;not null"`
+	Scope               string    `gorm:"size:256;default:''"`
+	Nonce               string    `gorm:"size:128;default:''"`
+	CodeChallenge       string    `gorm:"size:128;default:''"`
+	CodeChallengeMethod string    `gorm:"size:16;default:''"`
+	ExpiresAt           time.Time `gorm:"not null;index"`
+	Used                bool      `gorm:"default:false"`
+	CreatedAt           time.Time
+}