test: cover startup Caddyfile regeneration to prevent restart-loop regression

Adds TestStartupCaddyRegen::test_startup_regenerates_caddyfile_first,
asserting that _apply_startup_enforcement() calls
caddy_manager.regenerate_with_installed([]) before any peer/iptables work.
This pins the fix that ensures a stale on-disk Caddyfile (e.g. missing
`admin 0.0.0.0:2019`) is overwritten at startup and cannot cause the health
monitor to restart Caddy every few minutes.

Also restores two displaced lines in test_health_history_maxlen_evicts_old_entries.

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

tests/test_app_health_connectivity.py

@@ -62,6 +62,25 @@ class TestHealthHistoryIsDeque:
         assert hh[0]['n'] == 4
 
 
+# ---------------------------------------------------------------------------
+# startup regenerates the Caddyfile (stale-Caddyfile restart-loop fix)
+# ---------------------------------------------------------------------------
+
+class TestStartupCaddyRegen:
+    def test_startup_regenerates_caddyfile_first(self):
+        """_apply_startup_enforcement must regenerate the Caddyfile before
+        anything else, so a stale on-disk Caddyfile (e.g. missing
+        `admin 0.0.0.0:2019`) can't wedge the health monitor into restarting
+        Caddy every few minutes."""
+        with patch.object(app_module, 'caddy_manager') as mock_caddy, \
+             patch.object(app_module, 'peer_registry') as mock_pr:
+            # Raise right after the caddy regen to short-circuit the rest of
+            # the (heavy, docker/iptables) startup work.
+            mock_pr.list_peers.side_effect = RuntimeError('stop here')
+            app_module._apply_startup_enforcement()
+        mock_caddy.regenerate_with_installed.assert_called_once_with([])
+
+
 # ---------------------------------------------------------------------------
 # GET /api/health/history
 # ---------------------------------------------------------------------------