Add real-time system stats (CPU/RAM/GPU/VRAM) and fix favicon

Favicon now matches the LokiMark topbar icon instead of an unrelated
arrow glyph. New /api/system/stats endpoint (psutil + nvidia-smi)
polled every 2s and shown in the topbar next to the Ollama status.

backend/app/main.py

@@ -14,7 +14,7 @@ from fastapi.staticfiles import StaticFiles
 
 from . import db
 from .config import settings
-from .routes import chat, config, files, models, sessions, shell
+from .routes import chat, config, files, models, sessions, shell, system
 
 
 @asynccontextmanager
@@ -42,6 +42,7 @@ app.include_router(chat.router)
 app.include_router(files.router)
 app.include_router(config.router)
 app.include_router(shell.router)
+app.include_router(system.router)
 
 
 @app.get("/api/health")

backend/app/routes/system.py

@@ -0,0 +1,52 @@
+"""Statistiques système temps réel : CPU, RAM, GPU/VRAM (barre supérieure)."""
+from __future__ import annotations
+
+import asyncio
+import shutil
+
+import psutil
+from fastapi import APIRouter
+
+router = APIRouter(prefix="/api/system", tags=["system"])
+
+_NVIDIA_SMI = shutil.which("nvidia-smi")
+
+
+async def _gpu_stats() -> dict | None:
+    """Utilisation GPU/VRAM via nvidia-smi ; None si absent (pas de GPU NVIDIA)."""
+    if not _NVIDIA_SMI:
+        return None
+    try:
+        proc = await asyncio.create_subprocess_exec(
+            _NVIDIA_SMI,
+            "--query-gpu=utilization.gpu,memory.used,memory.total,name",
+            "--format=csv,noheader,nounits",
+            stdout=asyncio.subprocess.PIPE,
+            stderr=asyncio.subprocess.PIPE,
+        )
+        out, _ = await asyncio.wait_for(proc.communicate(), timeout=3)
+        line = out.decode().strip().splitlines()[0]
+        util, used, total, name = (p.strip() for p in line.split(","))
+        return {
+            "name": name,
+            "util_pct": float(util),
+            "vram_used_mb": float(used),
+            "vram_total_mb": float(total),
+        }
+    except Exception:
+        return None
+
+
+@router.get("/stats")
+async def stats() -> dict:
+    """CPU %, RAM et GPU/VRAM courants."""
+    cpu_pct = psutil.cpu_percent(interval=None)
+    mem = psutil.virtual_memory()
+    gpu = await _gpu_stats()
+    return {
+        "cpu_pct": cpu_pct,
+        "ram_used_go": round(mem.used / 1_000_000_000, 1),
+        "ram_total_go": round(mem.total / 1_000_000_000, 1),
+        "ram_pct": mem.percent,
+        "gpu": gpu,
+    }

backend/requirements.txt

@@ -3,3 +3,4 @@ uvicorn[standard]==0.34.0
 httpx==0.28.1
 pydantic==2.10.4
 pydantic-settings==2.7.1
+psutil==6.1.1