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/web/test_auth_async.py

@@ -0,0 +1,51 @@
+"""
+averify_password / ahash_password run bcrypt on a thread so the event
+loop can serve other requests while hashing. Contract: they must produce
+identical results to the sync versions.
+"""
+import pytest
+
+from decnet.web.auth import (
+    ahash_password,
+    averify_password,
+    get_password_hash,
+    verify_password,
+)
+
+
+@pytest.mark.asyncio
+async def test_ahash_matches_sync_hash_verify():
+    hashed = await ahash_password("hunter2")
+    assert verify_password("hunter2", hashed)
+    assert not verify_password("wrong", hashed)
+
+
+@pytest.mark.asyncio
+async def test_averify_matches_sync_verify():
+    hashed = get_password_hash("s3cret")
+    assert await averify_password("s3cret", hashed) is True
+    assert await averify_password("s3cre", hashed) is False
+
+
+@pytest.mark.asyncio
+async def test_averify_does_not_block_loop():
+    """Two concurrent averify calls should run in parallel (on threads).
+
+    With `asyncio.to_thread`, total wall time is ~max(a, b), not a+b.
+    """
+    import asyncio, time
+
+    hashed = get_password_hash("x")
+    t0 = time.perf_counter()
+    a, b = await asyncio.gather(
+        averify_password("x", hashed),
+        averify_password("x", hashed),
+    )
+    elapsed = time.perf_counter() - t0
+    assert a and b
+    # Sequential would be ~2× a single verify. Parallel on threads is ~1×.
+    # Single verify is ~250ms at rounds=12. Allow slack for CI noise.
+    single = time.perf_counter()
+    verify_password("x", hashed)
+    single_time = time.perf_counter() - single
+    assert elapsed < 1.7 * single_time, f"concurrent {elapsed:.3f}s vs single {single_time:.3f}s"