feat(auth): implement session-based token management with revocation support

Add Session model, SessionService, and SessionRepository to track user login
sessions and enable token revocation on auth-critical events.

- Introduce explicit TokenType (access/refresh) in JWT claims to prevent
  refresh token misuse via access token endpoints
- Add SessionID field to JWT claims, enabling stateless JWT validation
  against revoked sessions
- Replace legacy Auth middleware with RequireAuth/OptionalAuth pipeline
  that validates token type, account status, and session validity
- Implement session revocation on password change, reset, user ban/inactive,
  and explicit logout
- Add Principal cache with active invalidation for banned/role-changed users
- Fix IDOR vulnerability: GetMessagesByCursor now validates currentUserID
  is conversation participant via GetParticipantStrict
- Add group member visibility checks: announcements, group info, member list
  now require group membership
- Simplify Casbin policy: remove g grouping, use r.sub == p.sub matcher
  with globMatch; user_roles table is single source of truth for roles
- Add migration logic to clean legacy casbin g rules and migrate old p rules
  from path-style to admin/<domain> resource naming

internal/middleware/active.go

@@ -0,0 +1,35 @@
+package middleware
+
+import (
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+
+	"with_you/internal/pkg/auth"
+	"with_you/internal/pkg/response"
+)
+
+// RequireActive 要求账户状态为 active。
+//
+// 业务策略：
+//   - active：放行。
+//   - pending_deletion：在 /users/me/* 路由允许（用户可取消注销），但在 /admin/* 与敏感操作拒绝。
+//   - banned/inactive：已由 RequireAuth 在认证管道拦截，不会到达此处。
+//
+// 应挂在需要严格 active 状态的路由组上（如 /admin）。
+func RequireActive() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		p, ok := auth.GetPrincipal(c)
+		if !ok || p == nil {
+			response.ErrorWithStringCode(c, http.StatusUnauthorized, "UNAUTHORIZED", "未授权")
+			c.Abort()
+			return
+		}
+		if !p.IsActive() {
+			response.ErrorWithStringCode(c, http.StatusForbidden, "ACCOUNT_INACTIVE", "账号未激活")
+			c.Abort()
+			return
+		}
+		c.Next()
+	}
+}