Mobile notifications for iOS (#210)

* mobile: wire notification registration and listener

* implement backend components for push notifications

* refactor: agentic comment cleanup

* docs: use proper module name for particle processor

* set required env variables for push notifications

* bump version

* fix: always upsert push token on mobile start

* Revert "fix: always upsert push token on mobile start"

This reverts commit 90ff18a788.

* send push notifications regardless of online status

go/internal/pusher/channel.go

@@ -1,7 +1,7 @@
 package pusher
 
-// Channel tracks the local connections subscribed to a channel on this pod.
-// All methods are only called from the Hub goroutine — no locks needed.
+// Channel tracks the local connections subscribed on this pod.
+// State is only mutated by the Hub goroutine, so no locks are needed.
 type Channel struct {
 	id      string
 	members map[*Conn]string // conn → humanID
@@ -26,7 +26,7 @@ func (ch *Channel) isEmpty() bool {
 	return len(ch.members) == 0
 }
 
-// localHumanIDs returns the deduplicated set of humanIDs connected on this pod.
+// Deduplicated set; the same human may have multiple connections.
 func (ch *Channel) localHumanIDs() []string {
 	seen := make(map[string]bool, len(ch.members))
 	ids := make([]string, 0, len(ch.members))
@@ -39,7 +39,6 @@ func (ch *Channel) localHumanIDs() []string {
 	return ids
 }
 
-// hasHumanID returns true if the given humanID has at least one local connection.
 func (ch *Channel) hasHumanID(humanID string) bool {
 	for _, hid := range ch.members {
 		if hid == humanID {
@@ -49,7 +48,6 @@ func (ch *Channel) hasHumanID(humanID string) bool {
 	return false
 }
 
-// broadcast sends a message to all local connections except the excluded one.
 func (ch *Channel) broadcast(msg ServerMessage, exclude *Conn) {
 	for conn := range ch.members {
 		if conn != exclude {