fix: AI land-only bug — enforce 1-land/turn, populate legal moves, tune policy

Addresses the three root causes in commander-ai-lab-land-only-bug-analysis.md
plus several collateral fixes discovered along the way.

P0 — Land-per-turn enforcement (engine.py, deepseek_engine.py, turn_manager.py)
  * Guard _play_land() against double plays by tracking
    _lands_played_this_turn vs _land_plays_this_turn_limit on each player
  * Reset per-turn counters at the start of each player's turn
  * Ramp cards that grant additional plays can bump the limit

P0 — Legal move pipeline (new legal_move_generator.py, game_state.py)
  * New generate_legal_moves() emits the full macro-action set
    (play_land, cast_creature, cast_removal, cast_ramp, cast_draw,
    cast_commander, attack, block, pass_priority) based on phase,
    active player, land-drop state, mana, and commander tax
  * get_legal_moves() delegates to the new generator instead of the
    pass-only stub that blocked the turn_manager/policy-server path
  * apply_move() gains handlers for play_land, cast_spell,
    cast_commander, and declare_attacker — spells resolve to
    battlefield or graveyard, stats update correctly

P1 — Policy exploration (LearnedPolicy.java, scope.py)
  * Default greedy=false so the neural policy samples its
    distribution instead of always taking argmax
  * Raise ppo_entropy_coeff 0.01 → 0.04 to keep the action
    distribution flat during PPO self-play and prevent the
    pass/land collapse

Collateral fixes pulled in during the same session:
  * lan-client/precon-loader.js: await enrichAllZonesWithScryfall()
    so opening-hand cards have typeLine/cmc before the AI's first turn
  * lan-client/ui.js: closeZoneModal auto-shuffles the library
    whenever the zone modal closes
  * routes/game.py: BatchState() was missing total_games/threads,
    crashing POST /api/game/start
  * routes/deckgen.py: dead code after raise left headers undefined,
    breaking the Anthropic API path

All sim/phase/integration tests pass (650+).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

routes/deckgen.py

@@ -861,12 +861,13 @@ async def _call_anthropic_api(messages: list[dict], max_tokens: int = 4096, temp
     else:
         if not CFG.anthropic_api_key:
             raise HTTPException(400, 'Anthropic Claude API key not configured. Set anthropic_api_key env var or --anthropic-key.')
-            base_url = 'https://api.anthropic.com'
-            model = ANTHROPIC_MODEL
-            headers = {
+        base_url = 'https://api.anthropic.com'
+        model = ANTHROPIC_MODEL
+        headers = {
             'Content-Type': 'application/json',
-            'x-api-key': CFG.anthropic_api_key, 'anthropic-version': '2023-06-01',
-            }
+            'x-api-key': CFG.anthropic_api_key,
+            'anthropic-version': '2023-06-01',
+        }
     # Separate system messages for Anthropic API format
     system_msgs = [m['content'] for m in messages if m.get('role') == 'system']
     user_msgs = [m for m in messages if m.get('role') != 'system']

routes/game.py

@@ -147,7 +147,7 @@ async def start_game(req: StartGameRequest):
 
     # Build a BatchState so the forge_runner watchdog and progress tracking
     # work the same way they do for overnight batch runs.
-    state = BatchState(batch_id=game_id)
+    state = BatchState(batch_id=game_id, total_games=1, threads=1)
 
     _sessions[game_id] = {
         "game_id":         game_id,