add UI layer: dialogue stream, HUD, player menu, and skills panel

Runtime UI under Scripts/UI: a UIStateController owning menu/dialogue state, a
PlayerControlLock so opening a panel suppresses world input, panel visibility
helpers, and the menu input binding.

Views: the dialogue stream presenter and its options presenter and message row,
the portrait HUD, and the player menu with character, journal, and tab-bar
views. Skills gains SkillsPanelView and SkillRowView, which is why the Skills
asmdef now references UnityEngine.UI.

Prefabs/UI holds the authored canvases (dialogue stream, HUD, player menu) and
their rows. UILayerBootstrap remains a hand-added runtime fallback for scenes
where those prefabs are not instantiated; it deliberately does not auto-spawn.

Editor/UILayerSetup.cs is the one-shot menu that builds and wires those prefabs
into a scene, with UILayerSetupAutoRun reminding after a script reload.

Art/UI/Placeholder carries the placeholder portrait the HUD falls back to.

Co-Authored-By: Claude Opus 5 <[email protected]>

NightclubArcadia/Assets/Prefabs/UI/HudCanvas.prefab.meta

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