Feat: Add Token Stats and Cost Savings dashboard card and backend tracking

backend/routers/system.py

@@ -88,3 +88,25 @@ def self_update() -> dict:
     reset = _run(["git", "reset", "--hard", "origin/main"], cwd=SOURCE_DIR)
     restart_res = _run(["systemctl", "--user", "restart", "mission-control-2"])
     return {"pull": pull, "reset": reset, "restart": restart_res}
+
+
+from services.token_stats import get_stats
+
+@router.get("/system/token-stats")
+def token_stats() -> dict:
+    stats = get_stats()
+    p = stats.get("prompt_tokens", 0)
+    c = stats.get("completion_tokens", 0)
+    total = p + c
+    
+    # Blended savings based on a premium cloud model rate (e.g. GPT-4o / Claude 3.5 Sonnet: $3.00/1M input, $15.00/1M output)
+    saved_usd = (p * 3.0 + c * 15.0) / 1_000_000.0
+    saved_eur = saved_usd * 0.92  # 1 USD = 0.92 EUR
+    
+    return {
+        "prompt_tokens": p,
+        "completion_tokens": c,
+        "total_tokens": total,
+        "saved_usd": round(saved_usd, 2),
+        "saved_eur": round(saved_eur, 2)
+    }