First pass at full refactor to 2.0 design

Restructures the game around the cyclical run loop from Game Design Doc V2:
5 waves = a cycle, 3 cycles = a phase, each phase ends in a boss.

- New TD.Gameplay.Waves: WaveGroup / PhaseDefinition / RunDefinition author the
  run as draggable weighted pools; RunState owns phase/cycle position, the drawn
  wave slots, and the per-slot enemy buff sets. WaveManager's flat wave array is
  gone -- it now only runs the encounter RunState points at.
- New TD.Gameplay.EnemyUpgrades: the post-wave enemy-buff vote, with public
  live-replicated ballots so the HUD can show who voted for what.
- Inter-wave flow is now strictly sequential: draft -> vote -> build, each stage
  ending early once every player has acted.
- Enemy abilities inverted from per-instance random rolls to deterministic,
  stacking per-wave-slot sets. Six cards ship: Split (reworked), Flight, Blink,
  No Bounty, Gold Theft, Double Up.
- Tower upgrades are a two-step tree: a draft pick unlocks a node, gold converts
  an already-placed tower in place.
- Boss encounters flag their enemies and drive a boss HP bar.
- Player cap reduced to 3 via MatchRules.MaxPlayers.
- GoldConfig is now keyed by global encounter number rather than wave index.

Compiles clean; NOT yet verified in-engine. Editor wiring still required --
see Docs/2.0_Setup_Checklist.md.

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

Assets/_Project/Scripts/Gameplay/PlayerMatchState.cs

@@ -210,17 +210,21 @@ namespace TD.Gameplay
 
         // --- Slot allocation (server-only) -------------------------------
 
+        // Caps at MatchRules.MaxPlayers rather than at the PlayerSlot enum's range — the enum
+        // still runs to 9 so baked LevelData owner grids stay valid, but only the first
+        // MaxPlayers slots are ever handed out. See MatchRules for why.
         private static PlayerSlot AllocateNextSlot()
         {
-            for (int i = 1; i <= 9; i++)
+            for (int i = 1; i <= MatchRules.MaxPlayers; i++)
             {
                 var candidate = (PlayerSlot)i;
                 if (!s_assignedSlots.Contains(candidate))
                     return candidate;
             }
 
-            Debug.LogError("[PlayerMatchState] No free PlayerSlot (already 9 players). " +
-                           "Returning None — this client will be unable to play.");
+            Debug.LogError($"[PlayerMatchState] No free PlayerSlot (lobby is full at " +
+                           $"{MatchRules.MaxPlayers} players). Returning None — this client " +
+                           $"will be unable to play.");
             return PlayerSlot.None;
         }
     }