navigation: port value maps, features, skills, agent + dog-nav CLI

Copied from the dyna360 research stack into lerobot.navigation:

- value_map.py: DynaMem §3.4 exploration scoring (V_T recency + V_S
  query-similarity, combined value with distance discount).
- features.py: SiglipFeatureExtractor (MaskCLIP dense patches, lazy
  transformers) + FeatureExtractor protocol + BasisVectorFeatureExtractor
  stand-in for model-free dry-run/tests.
- skills.py: SpatialSkills locate/goto/explore over the voxel memory +
  base controller + text encoder.
- agent.py: DeterministicAgent (locate→goto / explore→relocate policy) +
  HardcodedTaskParser (regex NL→Task).
- sim.py: self-contained synthetic scenes (kitchen) + basis-vector text
  encoder, replacing the dyna360 eval harness for dry-run.
- dog_cli.py: `dog-nav` interactive REPL — idle→explore, prompt→locate+
  goto (explore-to-find on miss), preemptible, Ctrl-C e-stop, --dry-run.

Silenced benign fp16 matmul warnings in query/similarity via np.errstate.
Pure numpy + optional lazy torch/transformers; 67 new tests (116 total in
tests/navigation/), all model/hardware-free. Deliverable runs:
`python -m lerobot.navigation.dog_cli --dry-run`.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/navigation/test_dog_cli.py

@@ -0,0 +1,106 @@
+#!/usr/bin/env python
+
+# Copyright 2026 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""End-to-end dry-run tests for the dog-nav REPL + synthetic scene.
+
+These exercise the whole navigation stack — sim scene → voxel map →
+SigLIP stand-in → skills → agent → controller — with no robot, camera,
+or models.
+"""
+
+from __future__ import annotations
+
+import pytest
+
+from lerobot.navigation.dog_cli import DogController, _build_dry_run, main
+from lerobot.navigation.sim import kitchen_scene
+
+
+def test_kitchen_scene_builds_with_all_objects():
+    scene = kitchen_scene()
+    assert {o.name for o in scene.objects} == {"couch", "chair", "lamp", "plant"}
+    assert len(scene.voxel_map) > 0
+    assert scene.voxel_map.feature_dim == scene.feature_dim
+
+
+def test_feature_extractor_matches_object_vectors():
+    scene = kitchen_scene()
+    fx = scene.feature_extractor()
+    couch = scene.object("couch")
+    emb = fx.encode_text("couch")
+    # The couch query should align with the couch's stored basis vector.
+    import numpy as np
+
+    assert float(np.dot(emb, couch.feature_vec / np.linalg.norm(couch.feature_vec))) > 0.9
+
+
+def test_controller_reaches_mapped_object():
+    ctl = _build_dry_run()
+    result = ctl.handle_prompt("couch")
+    assert result.fully_successful
+    tr = result.target_results[0]
+    assert tr.reached
+    # Landed near the couch ground-truth (3.0, _, 2.0).
+    assert tr.final_xyz is not None
+    assert abs(tr.final_xyz[0] - 3.0) < 1.5
+    assert abs(tr.final_xyz[2] - 2.0) < 1.5
+
+
+def test_controller_navigates_to_each_object():
+    for name, (gx, gz) in {
+        "couch": (3.0, 2.0),
+        "chair": (-2.0, -1.5),
+        "plant": (-2.5, 2.5),
+    }.items():
+        ctl = _build_dry_run()
+        result = ctl.handle_prompt(name)
+        assert result.fully_successful, f"failed to reach {name}"
+        fx = result.target_results[0].final_xyz
+        assert abs(fx[0] - gx) < 1.5 and abs(fx[2] - gz) < 1.5
+
+
+def test_controller_abstains_on_absent_object():
+    ctl = _build_dry_run()
+    result = ctl.handle_prompt("banana")  # not in the scene
+    assert not result.fully_successful
+    assert result.target_results[0].reason in {"budget_exhausted", "no_frontier"}
+
+
+def test_idle_tick_explores_or_reports_no_frontier():
+    ctl = _build_dry_run()
+    ex = ctl.idle_tick()
+    # A fully-observed synthetic floor may have no frontier; either way the
+    # call must be well-formed and not raise.
+    assert ex.reason in {"ok", "no frontier"}
+
+
+def test_main_single_command_dry_run_returns_zero():
+    assert main(["--dry-run", "--command", "couch", "--log-level", "WARNING"]) == 0
+
+
+def test_main_absent_object_returns_nonzero():
+    assert main(["--dry-run", "--command", "banana", "--log-level", "WARNING"]) == 1
+
+
+def test_main_live_mode_refuses_until_pipeline_lands():
+    with pytest.raises(SystemExit):
+        main(["--command", "couch"])
+
+
+def test_dogcontroller_stop_is_safe():
+    ctl = _build_dry_run()
+    ctl.stop()
+    assert isinstance(ctl, DogController)