Give the sync progress bar colour and animation

The bar in the Sync popup is now an AnimatedProgressBar: taller, with a
darker track and the theme's accent fill (orange, frost blue in Nord, green
with a gold shine for Christmas). It shows Godot's busy animation until the
server reports progress, glides to each new value, has a soft highlight
sweeping along the filled part inside its rounded corners, and fills and
pops before the result shows. With Reduce animations it only jumps to its
values.

The styles are SyncProgressBar, SyncProgressBarFill and SyncProgressBarText
in every theme. Anim.stop stops a keyed animation without starting an empty
one.

The server now sends sync times as "MM:SS"; the spec is updated from
MusicServer develop (also the linux-package route), and the test data and
screenshots use the new format.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/integration/test_sync_popup.gd

@@ -10,6 +10,8 @@ var _window: Control
 func before_test() -> void:
 	_snapshot = AutoloadSnapshot.take([Settings])
 	Settings.currently_syncing = false
+	# The bar jumps to its values and the result shows at once
+	Settings.reduce_animations = true
 	_server = FakeHttpTransport.new().install()
 	_server.respond_bytes("/sync", PackedByteArray())
 	_runner = scene_runner("res://popups/SyncPopup.tscn")
@@ -38,7 +40,7 @@ func _empty_result() -> Dictionary:
 		"soundtracks_changed_content": [],
 		"soundtracks_removed": [],
 		"catched_errors": [],
-		"total_time": "00:00:03",
+		"total_time": "00:03",
 	}
 
 
@@ -64,12 +66,29 @@ func test_start_sync_does_nothing_while_already_syncing() -> void:
 
 func test_progress_updates_progress_bar() -> void:
 	_runner.invoke("start_sync")
-	_server.respond_json("/sync/progress", {"progress": "42", "time_spent": "00:00:12"})
+	_server.respond_json("/sync/progress", {"progress": "42", "time_spent": "00:12"})
 
 	_runner.invoke("_on_sync_timeout")
 
 	assert_float(_node("SyncProgressBar").value).is_equal(42.0)
-	assert_str(_node("SyncTime").text).is_equal("00:00:12")
+	assert_str(_node("SyncTime").text).is_equal("00:12")
+
+
+func test_finished_sync_fills_the_bar_before_the_result() -> void:
+	Settings.reduce_animations = false
+	_runner.invoke("start_sync")
+	var bar: AnimatedProgressBar = _node("SyncProgressBar")
+	assert_bool(bar.indeterminate).is_true()
+
+	_finish_sync(_empty_result())
+
+	assert_bool(_node("ProgressHBoxContainer").visible).is_true()
+	await await_millis(int(Anim.SLOW * 1000) + 100)
+	assert_float(bar.value).is_equal(100.0)
+	assert_bool(_node("ProgressHBoxContainer").visible).is_true()
+	await await_millis(int(Anim.SLOW * 1000) + 100)
+	assert_bool(_node("ProgressHBoxContainer").visible).is_false()
+	assert_str(_node("SyncTitleLabel").text).is_equal("Sync Result")
 
 
 func test_finished_sync_shows_only_sections_with_changes() -> void:
@@ -88,7 +107,7 @@ func test_finished_sync_shows_only_sections_with_changes() -> void:
 	assert_bool(_node("NoChangesLabel").visible).is_false()
 	# Header plus one label per soundtrack
 	assert_int(_node("SoundtracksAddedVBox").get_child_count()).is_equal(3)
-	assert_str(_node("SyncTime").text).is_equal("Total time: 00:00:03")
+	assert_str(_node("SyncTime").text).is_equal("Total time: 00:03")
 	assert_bool(Settings.currently_syncing).is_false()
 	await assert_signal(_window).is_emitted("sync_finished")