[feature] Push notifications (#3587)

* Update push subscription API model to be Mastodon 4.0 compatible

* Add webpush-go dependency

# Conflicts:
#	go.sum

* Single-row table for storing instance's VAPID key pair

* Generate VAPID key pair during startup

* Add VAPID public key to instance info API

* Return VAPID public key when registering an app

* Store Web Push subscriptions in DB

* Add Web Push sender (similar to email sender)

* Add no-op push senders to most processor tests

* Test Web Push notifications from workers

* Delete Web Push subscriptions when account is deleted

* Implement push subscription API

* Linter fixes

* Update Swagger

* Fix enum to int migration

* Fix GetVAPIDKeyPair

* Create web push subscriptions table with indexes

* Log Web Push server error messages

* Send instance URL as Web Push JWT subject

* Accept any 2xx code as a success

* Fix malformed VAPID sub claim

* Use packed notification flags

* Remove unused date columns

* Add notification type for update notifications

Not used yet

* Make GetVAPIDKeyPair idempotent

and remove PutVAPIDKeyPair

* Post-rebase fixes

* go mod tidy

* Special-case 400 errors other than 408/429

Most client errors should remove the subscription.

* Improve titles, trim body to reasonable length

* Disallow cleartext HTTP for Web Push servers

* Fix lint

* Remove redundant index on unique column

Also removes redundant unique and notnull tags on ID column since these are implied by pk

* Make realsender.go more readable

* Use Tobi's style for wrapping errors

* Restore treating all 5xx codes as temporary problems

* Always load target account settings

* Stub `policy` and `standard`

* webpush.Sender: take type converter as ctor param

* Move webpush.MockSender and noopSender into testrig

1 files changed, 17 insertions, 1 deletions

diff --git a/internal/cache/size.go b/internal/cache/size.go
index 24101683a..c96a3cd2e 100644
--- a/internal/cache/size.go
+++ b/internal/cache/size.go
@@ -66,6 +66,14 @@ you'll make society more equitable for all if you're not careful! :hammer_sickle
 	// be a serialized string of almost any type, so we pick a
 	// nice serialized key size on the upper end of normal.
 	sizeofResultKey = 2 * sizeofIDStr
+
+	// exampleWebPushAuth is a Base64-encoded 16-byte random auth secret.
+	// This secret is consumed as Base64 by webpush-go.
+	exampleWebPushAuth = "ZVxqlt5fzVgmSz2aqiA2XQ=="
+
+	// exampleWebPushP256dh is a Base64-encoded DH P-256 public key.
+	// This secret is consumed as Base64 by webpush-go.
+	exampleWebPushP256dh = "OrpejO16gV97uBXew/T0I7YoUv/CX8fz0z4g8RrQ+edXJqQPjX3XVSo2P0HhcCpCOR1+Dzj5LFcK9jYNqX7SBg=="
 )
 
 var (
@@ -576,7 +584,7 @@ func sizeofMove() uintptr {
 func sizeofNotification() uintptr {
 	return uintptr(size.Of(&gtsmodel.Notification{
 		ID:               exampleID,
-		NotificationType: gtsmodel.NotificationFave,
+		NotificationType: gtsmodel.NotificationFavourite,
 		CreatedAt:        exampleTime,
 		TargetAccountID:  exampleID,
 		OriginAccountID:  exampleID,
@@ -821,3 +829,11 @@ func sizeofUserMute() uintptr {
 		Notifications:   util.Ptr(false),
 	}))
 }
+
+func sizeofWebPushSubscription() uintptr {
+	return uintptr(size.Of(&gtsmodel.WebPushSubscription{
+		TokenID: exampleID,
+		Auth:    exampleWebPushAuth,
+		P256dh:  exampleWebPushP256dh,
+	}))
+}