refactor(tests): move flat tests/*.py into per-subsystem subfolders

Groups every flat test_*.py under the module it exercises, matching the
existing tests/{profiler,sniffer,prober,collector,correlation,cli,web,
topology,swarm,bus,updater,api,docker,geoip,...} layout. New folders:
services/, fleet/, config/, logging/, db/ (+ db/mysql/), telemetry/,
mutator/, core/.

Path-dependent __file__ references bumped an extra .parent in three
files that moved one level deeper:
- tests/sniffer/test_sniffer_ja3.py   (template path)
- tests/services/test_ssh_capture_emit.py (template path)
- tests/cli/test_mode_gating.py  (REPO root)
- tests/web/test_env_lazy_jwt.py (repo var)

Also drops two SQLite runtime artifacts (test_decnet.db-{shm,wal}) that
were leaking into the repo from a previous test run.

Fixes two test_service_isolation cases that patched asyncio.sleep (no
longer on the profiler main-loop hot path — same pre-existing bug I
fixed earlier in test_attacker_worker.py) by patching asyncio.wait_for
and passing interval=0.

tests/profiler/test_session_profile.py

@@ -0,0 +1,55 @@
+"""
+Tests for the session_profile table + repo helpers (SIGNAL_CAPTURE_AUDIT gap #2).
+
+Pre-v1 the ingestion job that populates keystroke-dynamics features is
+deferred; this suite exercises the empty-write path (one row per session,
+all feature columns NULL) and round-trips a filled row so future work can
+land without re-discovering the schema.
+"""
+import pytest
+from decnet.web.db.factory import get_repository
+
+
+@pytest.fixture
+async def repo(tmp_path):
+    r = get_repository(db_path=str(tmp_path / "session_profile.db"))
+    await r.initialize()
+    return r
+
+
+@pytest.mark.anyio
+async def test_empty_write_path_ships_null_features(repo):
+    # Session close writes `{}` — schema_version defaults to 1, all feature
+    # columns stay NULL.
+    await repo.upsert_session_profile("sid-1", {})
+    row = await repo.get_session_profile("sid-1")
+    assert row is not None
+    assert row["sid"] == "sid-1"
+    assert row["schema_version"] == 1
+    assert row["kd_iki_mean"] is None
+    assert row["kd_digraph_simhash"] is None
+    assert row["total_keystrokes"] is None
+
+
+@pytest.mark.anyio
+async def test_upsert_replaces_existing(repo):
+    await repo.upsert_session_profile("sid-2", {})
+    await repo.upsert_session_profile(
+        "sid-2",
+        {
+            "kd_iki_mean": 0.120,
+            "kd_iki_p95": 0.450,
+            "total_keystrokes": 512,
+            "session_duration_s": 61.3,
+        },
+    )
+    row = await repo.get_session_profile("sid-2")
+    assert row["kd_iki_mean"] == pytest.approx(0.120)
+    assert row["kd_iki_p95"] == pytest.approx(0.450)
+    assert row["total_keystrokes"] == 512
+    assert row["session_duration_s"] == pytest.approx(61.3)
+
+
+@pytest.mark.anyio
+async def test_get_missing_returns_none(repo):
+    assert await repo.get_session_profile("does-not-exist") is None