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/config/test_ini_validation.py

@@ -0,0 +1,41 @@
+import pytest
+from decnet.ini_loader import load_ini_from_string, validate_ini_string
+
+def test_validate_ini_string_too_large():
+    content = "[" + "a" * (512 * 1024 + 1) + "]"
+    with pytest.raises(ValueError, match="too large"):
+        validate_ini_string(content)
+
+def test_validate_ini_string_empty():
+    with pytest.raises(ValueError, match="is empty"):
+        validate_ini_string("")
+    with pytest.raises(ValueError, match="is empty"):
+        validate_ini_string("   ")
+
+def test_validate_ini_string_no_sections():
+    with pytest.raises(ValueError, match="no sections found"):
+        validate_ini_string("key=value")
+
+def test_load_ini_from_string_amount_limit():
+    content = """
+[general]
+net=192.168.1.0/24
+
+[decky-01]
+amount=101
+archetype=linux-server
+"""
+    with pytest.raises(ValueError, match="exceeds maximum allowed"):
+        load_ini_from_string(content)
+
+def test_load_ini_from_string_valid():
+    content = """
+[general]
+net=192.168.1.0/24
+
+[decky-01]
+amount=5
+archetype=linux-server
+"""
+    cfg = load_ini_from_string(content)
+    assert len(cfg.deckies) == 5