feat(compressors): add JSONL training metrics logging with CLI controls

- Add write_training_metrics() in new compressors/training_metrics.py
  for appending epoch/step/lr/component rows as JSON Lines
- Wire --metrics-path and --log-every CLI options into train.py, passing
  them to the training loop so metrics rows are written every N steps
- Accept absolute metrics paths or paths relative to output directory
- Add quantization component to loss log alongside existing distill/contrastive
- Replace inline torch.device() with get_device() utility
- Add test_hash_training_metrics.py covering multi-row JSONL append

Infrastructure:
- Pin torch 2.7.1 + CUDA 12.8 index for Linux/Windows in pyproject.toml
- Add .justfile rsync upload recipe with .stignore exclusion
- Exclude **/__marimo__ from rsync in .stignore

Dependencies updated: numpy 2.4.5, pandas 3.0.3, black 26.5.0,
click 8.4.0, contourpy, etc.

tests/test_hash_training_metrics.py

@@ -0,0 +1,61 @@
+import json
+import sys
+from pathlib import Path
+
+
+COMPRESSORS_DIR = Path(__file__).resolve().parents[1] / "mini-nav" / "compressors"
+sys.path.insert(0, str(COMPRESSORS_DIR))
+
+from training_metrics import write_training_metrics  # noqa: E402
+
+
+def test_write_training_metrics_appends_jsonl_rows(tmp_path):
+    metrics_path = tmp_path / "hash_training_metrics.jsonl"
+
+    write_training_metrics(
+        metrics_path,
+        epoch=2,
+        step=17,
+        lr=1e-4,
+        components={
+            "total": 1.25,
+            "contrastive": 0.75,
+            "distill": 0.4,
+            "quantization": 0.1,
+        },
+    )
+    write_training_metrics(
+        metrics_path,
+        epoch=2,
+        step=18,
+        lr=1e-4,
+        components={
+            "total": 1.0,
+            "contrastive": 0.6,
+            "distill": 0.3,
+            "quantization": 0.1,
+        },
+    )
+
+    rows = [json.loads(line) for line in metrics_path.read_text().splitlines()]
+
+    assert rows == [
+        {
+            "epoch": 2,
+            "step": 17,
+            "lr": 1e-4,
+            "total": 1.25,
+            "contrastive": 0.75,
+            "distill": 0.4,
+            "quantization": 0.1,
+        },
+        {
+            "epoch": 2,
+            "step": 18,
+            "lr": 1e-4,
+            "total": 1.0,
+            "contrastive": 0.6,
+            "distill": 0.3,
+            "quantization": 0.1,
+        },
+    ]