First-run onboarding: contextual coach-marks + How-to-Play card + dev replay toggle

Teaches the deep, interlocking loop — especially the inverted win condition
(you win by CLEARING EXPEDITIONS, not by surviving base sieges; DR-042/DR-043).

- OnboardingSystem: client-only observe-only PresentationSystemGroup overlay
  (own UIDocument @ sortingOrder 60), soft-gated 10-beat coach-mark sequence
  with a world-space ▶ pointer; never mutates sim / never destroys a ghost.
- OnboardingStepMath: pure, unit-tested step machine (snapshot + IsSatisfied +
  scheme-aware prompts + pointer kinds + persisted-mask helpers).
- HowToPlayPanel: tabbed reference card (Controls / The Loop / Build / Threats /
  Win-Lose), reachable from the main menu and the pause overlay.
- Per-client client-local state in GameSettings (TutorialHints + OnboardingMask
  bitmask, additive) — a Join client keeps its own; a host save-wipe never
  re-teaches. Settings toggle + menu "Replay Tutorial".
- Dev "Force Each Launch" toggle (GameSettings.ForceOnboardingEachLaunch):
  SettingsService.Boot wipes the mask + forces hints on in-memory every launch
  so the tutorial always replays fresh.
- HudSystem suppresses its own location hint while onboarding is active
  (single prompt voice), via OnboardingState + [UpdateAfter(OnboardingSystem)].

Validated green: 20/20 EditMode; Play smoke confirmed overlay render, clean
U+25B6 pointer glyph, no system sort-cycle, and the force-wipe end-to-end.

Docs: DR-043 + session log; reusable lesson archived in the build-gotchas note.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Assets/_Project/Scripts/Client/UI/MainMenuController.cs

@@ -18,6 +18,7 @@ namespace ProjectM.Client
         UIDocument _doc;
         VisualElement _mainPanel;
         VisualElement _settingsPanel;
+        VisualElement _howToPanel;
         TextField _ipField;
         Label _classLabel;
 
@@ -79,6 +80,21 @@ namespace ProjectM.Client
             card.Add(MenuUi.Button("Join", () => Launch(SessionMode.Join, false)));
 
             card.Add(MenuUi.Button("Settings", ShowSettings));
+            card.Add(MenuUi.Button("How to Play", ShowHowToPlay));
+
+            // Re-arm the first-run coach-marks (clears the client-local completed-step mask). The next session
+            // replays them; the How-to-Play card stays available regardless.
+            Button replayBtn = null;
+            replayBtn = MenuUi.Button("Replay Tutorial", () =>
+            {
+                var s = SettingsService.Current;
+                s.OnboardingMask = 0;
+                s.TutorialHints = 1;
+                SettingsService.Save(s);
+                if (replayBtn != null) replayBtn.text = "Tutorial armed ✓";
+            });
+            card.Add(replayBtn);
+
             card.Add(MenuUi.Button("Quit", Quit));
 
             _mainPanel.Add(card);
@@ -112,6 +128,19 @@ namespace ProjectM.Client
             _mainPanel.style.display = DisplayStyle.Flex;
         }
 
+        void ShowHowToPlay()
+        {
+            _mainPanel.style.display = DisplayStyle.None;
+            _howToPanel = HowToPlayPanel.Build(HideHowToPlay);
+            _doc.rootVisualElement.Add(_howToPanel);
+        }
+
+        void HideHowToPlay()
+        {
+            if (_howToPanel != null) { _howToPanel.RemoveFromHierarchy(); _howToPanel = null; }
+            _mainPanel.style.display = DisplayStyle.Flex;
+        }
+
         static void Quit()
         {
 #if UNITY_EDITOR