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/media/helpers.go

@@ -30,17 +30,15 @@ type TranscodeInput struct {
 type TranscodeOutput struct {
 	TempLocalFilePath string
 	OutputMimeType    string
-	// Extension such as ".m4a" or ".mp4"
-	OutputExt string
+	OutputExt         string // e.g. ".m4a" or ".mp4"
 }
 
 var (
 	ErrInvalidInput error = errors.New("invalid input")
 )
 
-// TranscodeToMp4 takes in any audio or video source URL and
-// returns the filepath of the transcoded media
-// WARNING: caller responsible for deleting TempLocalFilePath
+// TranscodeToMp4 writes the result to a temp file; caller is responsible
+// for deleting TempLocalFilePath.
 func TranscodeToMp4(ctx context.Context, input TranscodeInput) (*TranscodeOutput, error) {
 	if input.SourceURL == "" || input.MimeType == "" {
 		return nil, ErrInvalidInput
@@ -74,11 +72,9 @@ func TranscodeToMp4(ctx context.Context, input TranscodeInput) (*TranscodeOutput
 			tmpPath,
 		}
 	} else {
-		// Cap encoder parallelism and lookahead to keep memory bounded — screen
-		// recordings come in at native display resolution (often 1440p–4K) and
-		// libx264's per-thread lookahead/reference buffers blow past the worker's
-		// memory limit otherwise. Output is also downscaled to 1080p max, which
-		// mobile playback won't notice; the original WebM stays in GCS untouched.
+		// 1440p–4K screen recordings + libx264's lookahead buffers can OOM the
+		// worker. Bound parallelism/lookahead and downscale to 1080p; the
+		// original WebM stays in GCS untouched.
 		args = []string{
 			"-y", "-i", input.SourceURL,
 			"-vf", "scale='min(1920,iw)':-2:flags=lanczos",