test: raise coverage 68.7% -> ~80.4%; add ~250 tests for new egress/DDNS/network paths

Coverage was below acceptable levels and several newly-added code paths
(sshuttle egress, proxy egress, DDNS provider stubs, DNS overview route,
peer-registry provisioning) had zero test coverage.

~250 new unit tests are added across 16 new test files. Existing test files
are updated to match refactored interfaces (DHCP removed, constants
introduced, network_manager restructured). .coveragerc is added to pin the
source mapping and the 70% floor so regressions are caught at commit time.

tests/test_enhanced_api.py was previously living in api/ (wrong location)
and is moved to tests/ where it belongs.

Integration test files are updated to remove references to DHCP endpoints
and add coverage for the new DNS overview and DDNS sync endpoints.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/integration/test_network_services.py

@@ -1,10 +1,8 @@
 """
-Network services integration tests: DNS records, DHCP leases, DHCP reservations.
+Network services integration tests: DNS records, DNS overview.
 
 Note on endpoint shapes discovered from app.py:
-  - DELETE /api/dns/records      takes a JSON body (not a URL param)
-  - DELETE /api/dhcp/reservations takes JSON body with 'mac' field
-  - POST /api/dhcp/reservations   requires 'mac' and 'ip' fields
+  - DELETE /api/dns/records takes a JSON body (not a URL param)
 
 Run with:  pytest tests/integration/test_network_services.py -v
 """
@@ -129,79 +127,20 @@ class TestDnsRecordsWrite:
 
 
 # ---------------------------------------------------------------------------
-# GET /api/dhcp/leases
+# GET /api/dns/overview
 # ---------------------------------------------------------------------------
 
-class TestDhcpLeases:
-    def test_get_dhcp_leases_returns_200(self):
-        r = get('/api/dhcp/leases')
+class TestDnsOverview:
+    def test_get_dns_overview_returns_200(self):
+        r = get('/api/dns/overview')
         assert r.status_code == 200
 
-    def test_get_dhcp_leases_returns_list_or_dict(self):
-        data = get('/api/dhcp/leases').json()
-        assert isinstance(data, (list, dict))
-
-
-# ---------------------------------------------------------------------------
-# POST /api/dhcp/reservations  +  DELETE /api/dhcp/reservations
-# ---------------------------------------------------------------------------
-
-_TEST_MAC = 'de:ad:be:ef:11:22'
-_TEST_RESERVATION_IP = '10.0.0.200'
-
-
-class TestDhcpReservations:
-    def _cleanup(self):
-        delete('/api/dhcp/reservations', json={'mac': _TEST_MAC})
-
-    def test_add_dhcp_reservation_returns_non_error(self):
-        try:
-            r = post('/api/dhcp/reservations', json={
-                'mac': _TEST_MAC,
-                'ip': _TEST_RESERVATION_IP,
-                'hostname': 'inttest-dhcp-host',
-            })
-            assert r.status_code in (200, 201), (
-                f"Expected 200/201 for DHCP reservation, got {r.status_code}: {r.text}"
-            )
-        finally:
-            self._cleanup()
-
-    def test_add_dhcp_reservation_missing_mac_returns_400(self):
-        r = post('/api/dhcp/reservations', json={'ip': _TEST_RESERVATION_IP})
-        assert r.status_code == 400
-        assert 'error' in r.json()
-
-    def test_add_dhcp_reservation_missing_ip_returns_400(self):
-        r = post('/api/dhcp/reservations', json={'mac': _TEST_MAC})
-        assert r.status_code == 400
-        assert 'error' in r.json()
-
-    def test_add_dhcp_reservation_empty_body_returns_400(self):
-        r = post('/api/dhcp/reservations', data='')
-        assert r.status_code == 400
-
-    def test_delete_dhcp_reservation_missing_mac_returns_400(self):
-        r = delete('/api/dhcp/reservations', json={})
-        assert r.status_code == 400
-        assert 'error' in r.json()
-
-    def test_add_and_delete_dhcp_reservation_round_trip(self):
-        add_r = post('/api/dhcp/reservations', json={
-            'mac': _TEST_MAC,
-            'ip': _TEST_RESERVATION_IP,
-        })
-        assert add_r.status_code in (200, 201), (
-            f"Could not create DHCP reservation: {add_r.text}"
-        )
-        try:
-            del_r = delete('/api/dhcp/reservations', json={'mac': _TEST_MAC})
-            assert del_r.status_code in (200, 204), (
-                f"DHCP reservation delete failed: {del_r.status_code} {del_r.text}"
-            )
-        except Exception:
-            self._cleanup()
-            raise
+    def test_get_dns_overview_has_expected_keys(self):
+        data = get('/api/dns/overview').json()
+        assert isinstance(data, dict)
+        for key in ('mode', 'effective_domain', 'internal_domain',
+                    'public_records', 'internal_records'):
+            assert key in data
 
 
 # ---------------------------------------------------------------------------