feat: 新增「部署客户端」日志采集器模块

三种采集器（host-promtail / k8s-daemonset / k8s-fluentbit-sidecar），每种关联已部署 Loki：
- host-promtail：SSH 安装 Promtail（复用 deployBinary）
- k8s-daemonset：helm 安装 Promtail DaemonSet（复用 deployHelm）
- k8s-fluentbit-sidecar：kubectl patch 注入 Fluent Bit sidecar

含 Collector 数据模型、三个部署器、配置模板、CRUD API、前端页面。
附带 UI 优化：ErrorBoundary、部署卡片浏览器访问按钮、菜单名称调整。

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

backend/models/db.go

@@ -15,6 +15,7 @@ type JsonDB struct {
 	Hosts       []Host             `json:"hosts"`
 	Storages    []StorageConfig    `json:"storages"`
 	Deployments []LokiDeployment   `json:"deployments"`
+	Collectors  []Collector        `json:"collectors"`
 	Logs        []DeploymentLog    `json:"logs"`
 	Settings    []SystemSetting    `json:"settings"`
 	sequences   map[string]uint
@@ -37,6 +38,7 @@ func InitDB() error {
 		Hosts:     []Host{},
 		Storages:  []StorageConfig{},
 		Deployments: []LokiDeployment{},
+		Collectors:  []Collector{},
 		Logs:      []DeploymentLog{},
 		Settings:  []SystemSetting{},
 		sequences: map[string]uint{
@@ -45,6 +47,7 @@ func InitDB() error {
 			"hosts":       0,
 			"storages":    0,
 			"deployments": 0,
+			"collectors":  0,
 			"logs":        0,
 		},
 	}
@@ -57,6 +60,7 @@ func InitDB() error {
 			for _, h := range d.Hosts { if h.ID > d.sequences["hosts"] { d.sequences["hosts"] = h.ID } }
 			for _, s := range d.Storages { if s.ID > d.sequences["storages"] { d.sequences["storages"] = s.ID } }
 			for _, de := range d.Deployments { if de.ID > d.sequences["deployments"] { d.sequences["deployments"] = de.ID } }
+			for _, col := range d.Collectors { if col.ID > d.sequences["collectors"] { d.sequences["collectors"] = col.ID } }
 			for _, l := range d.Logs { if l.ID > d.sequences["logs"] { d.sequences["logs"] = l.ID } }
 		}
 	}