fix(doctor): honest module count, temp-path audit warning, connection line

Three doctor-page findings from the usertest panel:

- Module tile no longer counts the hub's built-in 'system'
  pseudo-module — a fresh hub shows 0 modules, matching the
  welcome checklist's definition of an install. Counting is a
  top-level function with unit tests.
- When the audit DB lives in an OS-cleanable temp directory
  (/var/folders, /tmp, Windows Temp), the daemon-files panel
  says so instead of presenting the state as healthy. The
  classifier is a top-level function with unit tests.
- The daemon card states who-talks-to-whom-how in one line:
  endpoint, transport security (TLS / unencrypted-local /
  unencrypted), and whether a bearer token is attached (length
  only) — the auditor's baseline the green dot cannot answer.

Also syncs pubspec.yaml (0.70.0 -> 0.72.0) with kStudioVersion,
which had drifted to 0.71.0 while pubspec stayed behind.

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

lib/data/hub.dart

@@ -1238,7 +1238,7 @@ class HubService {
     final paths = results[5] as DaemonPathsResponse;
 
     // Module count = distinct module_name across capabilities.
-    final moduleNames = <String>{for (final c in caps) c.moduleName};
+    final moduleNames = installedModuleNames(caps);
 
     // Per-source-kind breakdown (0.12+). Pre-0.12 hubs return
     // empty `source_kind` strings — group those under `kind`
@@ -1306,6 +1306,17 @@ class UpdateStatus {
   });
 }
 
+/// Distinct installed-module names behind a capability list.
+/// Excludes the hub's built-in `system` pseudo-module
+/// (`builtin_capabilities` reports `module_name: "system"`):
+/// the welcome checklist already treats `system.*` as "built
+/// in, not an install", and the doctor tile must count the
+/// same way — a fresh hub shows 0 modules, not 1.
+Set<String> installedModuleNames(Iterable<CapabilityEntry> caps) => {
+  for (final c in caps)
+    if (c.moduleName != 'system') c.moduleName,
+};
+
 class DoctorSnapshot {
   final int moduleCount;
   final int capabilityCount;