feat(us-016): mining-style node startup CLI + live dashboard

- `meshnet-node` with no args runs interactive setup wizard on first run,
  then starts directly on subsequent runs using saved config
- Wizard auto-detects all GPUs/VRAM, shows curated model list with per-quant
  VRAM requirements, marks models that exceed available VRAM as incompatible,
  offers HuggingFace Hub browse as escape hatch
- Persistent config saved to ~/.config/meshnet/config.json (0o600)
- Live rich dashboard (tokens/sec EMA, VRAM, requests, peers, uptime) with
  automatic plain-text fallback when stdout is not a TTY (WSL2/SSH/CI)
- All wizard values overridable via CLI flags; --reset-config re-runs wizard
- `meshnet-node models` lists curated models; `--browse` fetches HF Hub top-20
- `meshnet-node config` prints saved config
- `meshnet-node start ...` preserved for backward compatibility
- 19 new tests; 97 passed, 1 skipped (no regressions)

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

packages/node/meshnet_node/config.py

@@ -0,0 +1,72 @@
+"""Persistent node configuration — stored in ~/.config/meshnet/config.json."""
+
+from __future__ import annotations
+
+import json
+import os
+import stat
+from pathlib import Path
+
+_DEFAULT_CONFIG_DIR = Path.home() / ".config" / "meshnet"
+_DEFAULT_CONFIG_FILE = _DEFAULT_CONFIG_DIR / "config.json"
+_DEFAULT_DOWNLOAD_DIR = Path.home() / ".meshnet" / "models"
+_DEFAULT_TRACKER_URL = "http://localhost:8080"
+_DEFAULT_WALLET_PATH = str(Path.home() / ".config" / "meshnet" / "wallet.json")
+_DEFAULT_QUANTIZATION = "nf4"
+
+DEFAULTS = {
+    "model_hf_repo": "",
+    "model_name": "",
+    "quantization": _DEFAULT_QUANTIZATION,
+    "download_dir": str(_DEFAULT_DOWNLOAD_DIR),
+    "tracker_url": _DEFAULT_TRACKER_URL,
+    "wallet_path": _DEFAULT_WALLET_PATH,
+    "shard_start": None,
+    "shard_end": None,
+    "port": 7000,
+    "host": "0.0.0.0",
+}
+
+
+def config_path(override: Path | None = None) -> Path:
+    return override or _DEFAULT_CONFIG_FILE
+
+
+def load_config(path: Path | None = None) -> dict | None:
+    """Return parsed config dict, or None if no config file exists."""
+    p = config_path(path)
+    if not p.exists():
+        return None
+    try:
+        cfg = json.loads(p.read_text())
+        if not isinstance(cfg, dict):
+            return None
+        return cfg
+    except (json.JSONDecodeError, OSError):
+        return None
+
+
+def save_config(cfg: dict, path: Path | None = None) -> None:
+    """Write config to disk with restricted permissions (0o600)."""
+    p = config_path(path)
+    p.parent.mkdir(parents=True, exist_ok=True)
+    p.write_text(json.dumps(cfg, indent=2))
+    try:
+        os.chmod(p, stat.S_IRUSR | stat.S_IWUSR)
+    except OSError:
+        pass  # Windows / some filesystems don't support chmod
+
+
+def delete_config(path: Path | None = None) -> None:
+    p = config_path(path)
+    if p.exists():
+        p.unlink()
+
+
+def merge_cli_overrides(cfg: dict, **cli_kwargs) -> dict:
+    """Return a copy of cfg with any non-None CLI values applied on top."""
+    result = dict(cfg)
+    for key, val in cli_kwargs.items():
+        if val is not None:
+            result[key] = val
+    return result