[chore] media pipeline improvements (#3110)

* don't set emoji / media image paths on failed download, migrate FileType from string to integer

* fix incorrect uses of util.PtrOr, fix returned frontend media

* fix migration not setting arguments correctly in where clause

* fix not providing default with not null column

* whoops

* ensure a default gets set for media attachment file type

* remove the exclusive flag from writing files in disk storage

* rename PtrOr -> PtrOrZero, and rename PtrValueOr -> PtrOrValue to match

* slight wording changes

* use singular / plural word forms (no parentheses), is better for screen readers

* update testmodels with unknown media type to have unset file details, update attachment focus handling converting to frontend, update tests

* store first instance in ffmpeg wasm pool, fill remaining with closed instances

internal/media/ffmpeg/pool.go

@@ -34,14 +34,33 @@ type wasmInstancePool struct {
 }
 
 func (p *wasmInstancePool) Init(ctx context.Context, sz int) error {
-	p.pool = make(chan *wasm.Instance, sz)
-	for i := 0; i < sz; i++ {
-		inst, err := p.inst.New(ctx)
-		if err != nil {
-			return err
-		}
-		p.pool <- inst
+	// Initialize for first time
+	// to preload module into the
+	// wazero compilation cache.
+	inst, err := p.inst.New(ctx)
+	if err != nil {
+		return err
 	}
+
+	// Clamp to 1.
+	if sz <= 0 {
+		sz = 1
+	}
+
+	// Allocate new pool instance channel.
+	p.pool = make(chan *wasm.Instance, sz)
+
+	// Store only one
+	// open instance
+	// at init time.
+	p.pool <- inst
+
+	// Fill reminaing with closed
+	// instances for later opening.
+	for i := 0; i < sz-1; i++ {
+		p.pool <- new(wasm.Instance)
+	}
+
 	return nil
 }