feat: AI Dungeon Master engine + web frontend

- Engine: stato SQLite, state machine, 10 approved tools, parser azioni
- LLM: multi-provider (Ollama/OpenRouter/Local), system prompt DCC
- DM cycle: LLM decide tool → engine esegue → narrazione + meccanica
- Dati avventura: JSON machine-readable con 9 aree, mostri, enigmi, quest
- Web: FastAPI + WebSocket backend, SPA frontend dark fantasy
- Ref: architecture-patterns/neon-scratch-lounge (separazione reasoning/execution)

src/engine/dm.py

@@ -0,0 +1,110 @@
+from __future__ import annotations
+
+import logging
+
+from src.engine import db, tools
+from src.engine.config import load_from_env
+from src.engine.llm import ask as llm_ask, parse_tool_call
+from src.engine.prompts import SYSTEM_PROMPT, build_prompt
+from src.engine.state_machine import GameContext, _parse_action
+
+log = logging.getLogger(__name__)
+
+
+def _llm_decision(ctx: GameContext, player_action: str) -> tuple[str, dict, str]:
+    prompt = build_prompt(ctx, player_action)
+    try:
+        raw = llm_ask(prompt, system=SYSTEM_PROMPT)
+    except Exception as e:
+        log.warning("LLM call failed (%s), fallback a _parse_action", e)
+        tool, params = _parse_action(player_action, ctx)
+        return tool, params, ""
+
+    decision = parse_tool_call(raw)
+
+    tool = decision.get("tool", "")
+    params = decision.get("params", {})
+    narration = decision.get("narration", "")
+
+    if not tool:
+        log.info("LLM non ha prodotto tool valido, fallback heuristico")
+        tool, params = _parse_action(player_action, ctx)
+
+    return tool, params, narration
+
+
+def dm_cycle(campaign_id: int, player_action: str) -> dict:
+    ctx = GameContext.load(campaign_id)
+
+    tool_name, tool_params, narration = _llm_decision(ctx, player_action)
+
+    result = tools.run(tool_name, **tool_params)
+
+    mechanic_msg = result.get("message", "")
+    full_msg = f"{narration}\n{mechanic_msg}".strip()
+
+    turn = db.advance_turn(campaign_id)
+    db.log_turn(campaign_id, turn, player_action, full_msg)
+
+    return {
+        "turn": turn,
+        "action": player_action,
+        "tool": tool_name,
+        "params": tool_params,
+        "narration": narration,
+        "mechanics": mechanic_msg,
+        "full_output": full_msg,
+    }
+
+
+def interactive(campaign_id: int):
+    cfg = load_from_env()
+    print("=" * 60)
+    print("DCC RPG — AI Dungeon Master")
+    print(f"Provider: {cfg.kind}  |  Modello: {getattr(cfg, f'{cfg.kind}_model', '?')}")
+    print("Scrivi 'esci' per uscire, 'stato' per vedere la scheda.")
+    print("=" * 60)
+    print()
+
+    ctx = GameContext.load(campaign_id)
+    print(ctx.summary())
+    print()
+
+    while True:
+        try:
+            action = input("⚔️  » ").strip()
+        except (EOFError, KeyboardInterrupt):
+            print("\nFine partita.")
+            break
+
+        if not action:
+            continue
+        if action.lower() in ("esci", "exit", "quit"):
+            print("Alla prossima avventura!")
+            break
+        if action.lower() in ("stato", "stat", "status"):
+            print(GameContext.load(campaign_id).summary())
+            continue
+
+        print("🎲  Elaborazione...")
+        out = dm_cycle(campaign_id, action)
+        print(f"\n📖 {out['narration'] or '(azione riconosciuta)'}")
+        if out['mechanics']:
+            print(f"⚙️  {out['mechanics']}")
+        print()
+
+
+if __name__ == "__main__":
+    import sys
+
+    db.init_db()
+    camp_id = db.create_campaign("Avventura Test", "Tomba del Mago-Guerriero")
+    char_id = db.create_character(camp_id, "Marco il Fidato", "guerriero", "soldato")
+    db.update_character(
+        char_id,
+        level=1, str=15, agi=11, sta=14,
+        per=9, int=8, lck=10,
+        hp_current=12, hp_max=12, ac=15,
+        armor_type="light",
+    )
+    interactive(camp_id)