Rework the UI on Crusenho's pack; credit it in the game, not just the repo

Crusenho's Complete UI Essential Pack is CC BY 4.0 -- redistributable and
commercial-friendly, confirmed from the License.txt the pack itself ships --
so unlike the two bdragon packs a subset is committed: twelve PNGs, 48 KB,
under assets/sprites/ui/. Only what is used, because each committed PNG costs
a Godot .import sidecar and a directory nothing references is one nobody
prunes.

UiTheme builds a Theme in code from it -- button states, panels, line edits --
and every screen roots itself through UiTheme.themed_root(). The HUD's bars are
the pack's frame with a tinted fill, drawn as three horizontal slices because
Godot's nine-patch lives on nodes and the HUD is drawn rather than built from
controls. Inventory slots use the pack's slot art at exactly twice the source
size; a non-integer scale on a 1px border reads as a wobble along every edge.

The credits screen is the other half of the request and it is a licence
obligation, not a nicety: two packs are now CC BY, which asks for attribution
"in any reasonable manner", and a markdown file in a source repo is not
reasonable for someone who downloaded a build. Settings -> Credits shows every
source with its terms and a link to the licence text. test_credits.gd asserts
CREDITS.md and docs/ASSETS.md name every entry, so the three cannot drift.

Two things found by actually looking at the screen, which is the point:

  - The FIRST version of this styled nothing. A Control inherits its theme from
    Control ANCESTORS only, and the chain breaks at the first plain Node or
    CanvasLayer -- which is every screen here. get_window().theme set the
    property, changed nothing, and read as correct. check.sh, 458 tests and a
    clean smoke run all passed with the entire interface unstyled. The theme
    test now instantiates every screen and asks what its buttons resolve.
  - The settings screen showed Fire bound to the right mouse button, because
    the test suite was writing the player's real user://settings.cfg --
    rebinding calls save() and nothing had redirected the path. Settings.path
    is now redirectable, the fixture points it at a scratch file, and a test
    asserts the default is still the player's own.

tools/screenshot.tscn is what found both. It boots the client windowed and
saves the menus, the HUD, settings and credits. Manual, needs a display, and
the only thing in the project that can tell you the interface rendered.

check.sh clean, 460 tests, SMOKE PASS, all four diagnostics green.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tools/screenshot.gd

@@ -0,0 +1,86 @@
+extends Node
+## Boot the client windowed, capture a few screens, and quit.
+##
+##   SHOT_DIR=/tmp/shots godot --path . res://tools/screenshot.tscn
+##
+## This exists because UI is the one part of the game the rest of the tooling
+## cannot check. `check.sh` proves it parses, the suite proves the theme
+## resolves, the smoke test proves nothing errors -- and all three passed
+## while the entire interface rendered unstyled, because Godot's theme
+## inheritance breaks at the first non-Control parent and nothing had ever
+## looked at the screen.
+##
+## Needs a real display, so it is not part of any automated gate. Run it after
+## touching anything under src/ui/ and open the files.
+
+const GAME := preload("res://src/game.tscn")
+## Frame numbers, not seconds: the point is a deterministic sequence, and a
+## windowed client at 60fps gets there in about four seconds.
+const AT_MENU := 30
+const ENTER_GAME := 34
+const AT_GAME := 200
+const OPEN_MENU := 210
+const AT_INGAME_MENU := 240
+const OPEN_SETTINGS := 250
+const AT_SETTINGS := 280
+const OPEN_CREDITS := 290
+const AT_CREDITS := 320
+const DONE := 330
+
+var _frame: int = 0
+var _game: Node = null
+var _menu: Control = null
+var _dir: String = "user://"
+
+
+func _ready() -> void:
+	GameOpts.parse()
+	Engine.physics_ticks_per_second = SimConfig.TICK_RATE
+	Settings.load_and_apply()
+	var from_env := OS.get_environment("SHOT_DIR")
+	if not from_env.is_empty():
+		_dir = from_env
+	get_window().size = Vector2i(1280, 720)
+	_menu = preload("res://src/ui/main_menu.gd").new()
+	add_child(_menu)
+
+
+func _process(_delta: float) -> void:
+	_frame += 1
+	match _frame:
+		AT_MENU:
+			_grab("menu")
+		ENTER_GAME:
+			_menu.queue_free()
+			Net.host(27455)
+			Net.start_local_client()
+			_game = GAME.instantiate()
+			add_child(_game)
+		AT_GAME:
+			_grab("game")
+		OPEN_MENU:
+			_game.get_node("GameMenu").open()
+		AT_INGAME_MENU:
+			_grab("menu_ingame")
+		OPEN_SETTINGS:
+			_game.get_node("GameMenu").close()
+			_game.get_node("SettingsScreen").open()
+		AT_SETTINGS:
+			_grab("settings")
+		OPEN_CREDITS:
+			_game.get_node("SettingsScreen").visible = false
+			_game.get_node("CreditsScreen").open()
+		AT_CREDITS:
+			_grab("credits")
+		DONE:
+			Net.shutdown()
+			get_tree().quit(0)
+
+
+func _grab(shot_name: String) -> void:
+	var path := "%s/shot_%s.png" % [_dir, shot_name]
+	var err := get_viewport().get_texture().get_image().save_png(path)
+	if err != OK:
+		printerr("could not write %s (error %d)" % [path, err])
+		return
+	print("saved ", path)

tools/screenshot.gd.uid

@@ -0,0 +1 @@
+uid://bnuqy4w5whjce

tools/screenshot.tscn

@@ -0,0 +1,6 @@
+[gd_scene load_steps=2 format=3]
+
+[ext_resource type="Script" path="res://tools/screenshot.gd" id="1"]
+
+[node name="Screenshot" type="Node"]
+script = ExtResource("1")