推送通知：Web Push（网页 / PWA）+ 桌面原生通知

页面 / PWA 关闭、或桌面窗口非前台时，收到文件、消息、传输完成 / 失败以系统通知提醒。
判定统一为「页面打开走应用内提示，否则系统通知」，三端各自落地；网页端的判定直接复用
Hub.SendTo 的投递结果，零额外状态。

- Web Push（VAPID，账号无关）：服务端 internal/push.Sender 在事件未经 SSE 投递到目标
  设备时（即该设备页面已关）发推送，文案按订阅 locale 在服务端渲染（中简 / 中繁 / 英）、
  404 / 410 自动清理死订阅；新增 push_subscriptions 表（含 locale，主键为 endpoint 的
  SHA-256 以幂等 upsert）+ /api/push/{vapid-key, subscribe POST/DELETE} 端点
- 事件挂接：transfer:incoming / message（离线返 202，文本随推送送达）/ transfer:state
  DONE|FAILED，均未投递才推
- 配置 CDROP_VAPID_PUBLIC_KEY / CDROP_VAPID_PRIVATE_KEY（半对即拒启动，都空则推送惰性
  关闭）+ just vapid-keygen 生成工具（cmd/vapidgen）
- 前端：service worker 加 push / notificationclick（仍不拦截 /api 与导航）；net/push.ts
  订阅管理 + push store slice + 设置页「推送通知」面板（仅浏览器 / PWA）；登录后 resyncPush
  把既有订阅重新登记到当前用户，换用户 / endpoint 轮换 / 切换语言皆自愈
- 桌面原生通知：platform/notify_{darwin,windows,other}.go + notify_darwin.m，仅窗口非
  前台时弹原生通知（macOS UNUserNotificationCenter，未签名时安全空操作、待签名后显示；
  Windows go-toast 即用）；app.go ShowNotification 绑定，前端 notifyNativeIfBackground
  复用 hub 事件分发 + 客户端本地化
- 文档：README / .env.example / compose 模板补 CDROP_VAPID_* 配置

注：sqlc v1.31.1 对 query 文件里的多字节字符会错位偏移、生成损坏 SQL，故 query 注释保持纯
ASCII（文件内留有警示）。

internal/config/config.go

@@ -3,6 +3,7 @@ package config
 import (
 	"errors"
 	"fmt"
+	"net/url"
 	"os"
 	"strings"
 
@@ -72,6 +73,15 @@ type Config struct {
 	// 文本（密码.app / 浏览器扩展复制都不打敏感标记），改以短 TTL 限制暴露面：
 	// 内容超过 TTL 后 GET 返回空，后台 sweeper 亦清除其 content。0 = 不过期。
 	ClipboardTTLSec int `koanf:"clipboard_ttl_sec"`
+
+	// Web Push (RFC 8291/8292)：浏览器 / PWA 在页面关闭时仍能收到系统通知。
+	// 公私钥是自签的 VAPID 密钥对（与 Apple/Google 账号无关），用 `just vapid-keygen`
+	// 生成一次后固定——更换会使所有既有订阅失效。两者皆设才启用推送，缺一即整体
+	// 关闭（订阅端点返回 503，事件回退为「仅在线设备收 SSE」）。Subject 是 VAPID
+	// 要求的联系标识（mailto: 或站点 URL）；留空时回退为部署站点 URL。
+	VAPIDPublicKey  string `koanf:"vapid_public_key"`
+	VAPIDPrivateKey string `koanf:"vapid_private_key"`
+	VAPIDSubject    string `koanf:"vapid_subject"`
 }
 
 // Load reads config from optional ./config.yaml then overrides with CDROP_* env.
@@ -145,5 +155,32 @@ func (c *Config) validate() error {
 	default:
 		return fmt.Errorf("CDROP_AUTH_MODE must be \"dev\" or \"prod\", got %q", c.AuthMode)
 	}
+
+	// Web Push is optional, but a half-configured pair is always an operator
+	// mistake: with only one key set, every push send would fail at runtime
+	// while the feature looks "on". Fail fast instead of silently degrading.
+	if (c.VAPIDPublicKey == "") != (c.VAPIDPrivateKey == "") {
+		return errors.New(
+			"CDROP_VAPID_PUBLIC_KEY and CDROP_VAPID_PRIVATE_KEY must be set together " +
+				"(run `just vapid-keygen`); set neither to disable Web Push")
+	}
 	return nil
 }
+
+// PushEnabled reports whether Web Push is configured (both VAPID keys present).
+func (c *Config) PushEnabled() bool {
+	return c.VAPIDPublicKey != "" && c.VAPIDPrivateKey != ""
+}
+
+// VAPIDSubjectOrDefault returns the VAPID contact identity. Push services want a
+// way to reach the operator; the configured value wins, else the deployment's
+// own origin (derived from the OIDC redirect URI), else the product URL.
+func (c *Config) VAPIDSubjectOrDefault() string {
+	if c.VAPIDSubject != "" {
+		return c.VAPIDSubject
+	}
+	if u, err := url.Parse(c.OIDCRedirectURI); err == nil && u.Scheme != "" && u.Host != "" {
+		return u.Scheme + "://" + u.Host
+	}
+	return "https://drop.commilitia.net"
+}

internal/config/config_test.go

@@ -56,6 +56,51 @@ func TestValidate_ProdRequiresAudience(t *testing.T) {
 	}
 }
 
+func TestValidate_VAPIDHalfPairRejected(t *testing.T) {
+	// A single VAPID key is always an operator mistake: every push would fail at
+	// runtime while the feature reads as "on". Reject either half alone.
+	pubOnly := &Config{AuthMode: "dev", DevToken: "x", VAPIDPublicKey: "pub"}
+	if err := pubOnly.validate(); err == nil {
+		t.Fatal("public key without private must reject")
+	}
+	privOnly := &Config{AuthMode: "dev", DevToken: "x", VAPIDPrivateKey: "priv"}
+	if err := privOnly.validate(); err == nil {
+		t.Fatal("private key without public must reject")
+	}
+}
+
+func TestValidate_VAPIDBothOrNeitherOK(t *testing.T) {
+	both := &Config{AuthMode: "dev", DevToken: "x", VAPIDPublicKey: "pub", VAPIDPrivateKey: "priv"}
+	if err := both.validate(); err != nil {
+		t.Fatalf("both VAPID keys should pass; got %v", err)
+	}
+	if !both.PushEnabled() {
+		t.Fatal("PushEnabled should be true when both keys set")
+	}
+	neither := &Config{AuthMode: "dev", DevToken: "x"}
+	if err := neither.validate(); err != nil {
+		t.Fatalf("no VAPID keys should pass (push disabled); got %v", err)
+	}
+	if neither.PushEnabled() {
+		t.Fatal("PushEnabled should be false when no keys set")
+	}
+}
+
+func TestVAPIDSubjectOrDefault(t *testing.T) {
+	explicit := &Config{VAPIDSubject: "mailto:ops@example.com"}
+	if got := explicit.VAPIDSubjectOrDefault(); got != "mailto:ops@example.com" {
+		t.Fatalf("explicit subject: got %q", got)
+	}
+	derived := &Config{OIDCRedirectURI: "https://drop.example.com/oauth/callback"}
+	if got := derived.VAPIDSubjectOrDefault(); got != "https://drop.example.com" {
+		t.Fatalf("derived subject: got %q, want scheme://host", got)
+	}
+	fallback := &Config{}
+	if got := fallback.VAPIDSubjectOrDefault(); !strings.HasPrefix(got, "https://") {
+		t.Fatalf("fallback subject should be an https URL; got %q", got)
+	}
+}
+
 func TestValidate_UnknownMode(t *testing.T) {
 	c := &Config{AuthMode: "rogue"}
 	err := c.validate()