feat: 新增语音转文字（ASR）功能

- 后端：新增 /api/audio/transcribe 接口，调用 Ollama whisper 进行语音识别
- 前端：新增 AudioTranscribePage.vue 页面，支持 MP3/WAV/M4A/OGG/FLAC 等格式
- 注册路由、工具卡片、智能助手欢迎语更新

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

eai_agentplatform/backend-go/internal/api/auth.go

@@ -0,0 +1,75 @@
+package api
+
+import (
+	"github.com/gin-gonic/gin"
+
+	"eai_agentplatform/backend/internal/auth"
+	"eai_agentplatform/backend/internal/middleware"
+	"eai_agentplatform/backend/internal/model"
+	"eai_agentplatform/backend/internal/store"
+	"eai_agentplatform/backend/internal/web"
+)
+
+type loginRequest struct {
+	Username string `json:"username"`
+	Password string `json:"password"`
+}
+
+// Login 登录 → JWT
+func Login(c *gin.Context) {
+	var req loginRequest
+	if err := c.ShouldBindJSON(&req); err != nil {
+		web.Fail(c, web.NewBadRequest("请求参数错误"))
+		return
+	}
+
+	var user model.User
+	if err := store.DB.Where("username = ?", req.Username).First(&user).Error; err != nil {
+		web.Fail(c, web.NewAuthError("用户名或密码错误"))
+		return
+	}
+	if user.Status != "active" {
+		web.Fail(c, web.NewAuthError("账号已禁用"))
+		return
+	}
+	if !auth.VerifyPassword(req.Password, user.PasswordHash) {
+		web.Fail(c, web.NewAuthError("用户名或密码错误"))
+		return
+	}
+
+	token, err := auth.CreateToken(user.Username, user.Role, Cfg.JWTSecret, Cfg.JWTExpireMin)
+	if err != nil {
+		web.Fail(c, web.NewBadRequest("令牌签发失败"))
+		return
+	}
+
+	web.OK(c, gin.H{
+		"token":      token,
+		"expires_in": Cfg.JWTExpireMin * 60,
+		"user": gin.H{
+			"id":        user.ID,
+			"username":  user.Username,
+			"full_name": user.FullName,
+			"role":      user.Role,
+			"ai_points": user.AiPoints,
+		},
+	})
+}
+
+// Me 当前用户信息
+func Me(c *gin.Context) {
+	u := middleware.CurrentUser(c)
+	if u == nil {
+		web.Fail(c, web.NewAuthError("未登录"))
+		return
+	}
+	web.OK(c, gin.H{
+		"id":              u.ID,
+		"username":        u.Username,
+		"full_name":       u.FullName,
+		"role":            u.Role,
+		"status":          u.Status,
+		"ai_points":       u.AiPoints,
+		"learning_points": u.LearningPoints,
+	})
+}