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/billing/usage_models.go

@@ -2,11 +2,9 @@ package billing
 
 import "time"
 
-// FreemiumDailyLimit is the per-network daily cap on usage,
-// agnostic of the units that this refer to. This is only relevant for the "free" plan.
+// Per-network daily cap on the free plan. Unit-agnostic.
 const FreemiumDailyLimit = 50
 
-// Usage describes a network's current freemium quota state for today.
 type Usage struct {
 	Plan    Plan      `json:"plan"`
 	Used    int       `json:"used"`