Series UI: update copy to speak about branches

At least for now, its more familiar terminology

apps/desktop/src/lib/branch/StackingSeriesHeader.svelte

@@ -221,10 +221,10 @@
 		<div class="branch-emptystate">
 			<EmptyStatePlaceholder bottomMargin={10}>
 				{#snippet title()}
-					This is an empty series
+					This is an empty branch
 				{/snippet}
 				{#snippet caption()}
-					All your commits will land here
+					Create or drag and drop commits here
 				{/snippet}
 			</EmptyStatePlaceholder>
 		</div>

apps/desktop/src/lib/branch/StackingSeriesHeaderContextMenu.svelte

@@ -73,7 +73,7 @@
 		/>
 		{#if $aiGenEnabled && aiConfigurationValid && !disableTitleEdit}
 			<ContextMenuItem
-				label="Generate series name"
+				label="Generate branch name"
 				onclick={() => {
 					onGenerateBranchName();
 					contextMenuEl?.close();
@@ -121,7 +121,7 @@
 
 <Modal
 	width="small"
-	title="Rename series"
+	title="Rename branch"
 	bind:this={renameSeriesModal}
 	onSubmit={(close) => {
 		if (newHeadName && newHeadName !== headName) {
@@ -140,7 +140,7 @@
 
 <Modal
 	width="small"
-	title="Delete series"
+	title="Delete branch"
 	bind:this={deleteSeriesModal}
 	onSubmit={async (close) => {
 		try {