fix: 修复19个Bug (P0-P3) — 持续性调试第7轮发现的问题

P0 (5): crypto/rand session ID, TTS fallback可达性, goroutine defer recover, adminAuth前缀修正
P1 (5): 普通用户密码验证, context传递, priority clamp, 超时重试, 自主思考速率限制
P2 (4): Briefing AI降级, 前端消息类型渲染, Docker Compose补全, PWA 192图标
P3 (5): goroutine错误处理, .gitignore完善, reminder created_at, voice Dockerfile, Go版本更新

backend/memory-service/Dockerfile

@@ -1,5 +1,5 @@
 # Build stage
-FROM golang:1.24-alpine AS builder
+FROM golang:1.26-alpine AS builder
 
 WORKDIR /app
 COPY go.mod go.sum ./

backend/memory-service/internal/service/memory_service.go

@@ -37,9 +37,14 @@ func (svc *MemoryService) CreateMemory(ctx context.Context, entry *model.MemoryE
 	if entry.Importance < 1 {
 		entry.Importance = 5
 	}
-	if entry.Priority < 0 || entry.Priority > 3 {
+	// Priority 范围检查：扩展为 [0, 10] 以支持用户自定义高优先级记忆
+	// 低于 0 的视为无效，重置为 normal；高于 10 的截断到 10
+	if entry.Priority < 0 {
 		entry.Priority = model.MemoryNormal
 	}
+	if entry.Priority > 10 {
+		entry.Priority = 10
+	}
 	if entry.Source == "" {
 		entry.Source = "manual"
 	}