fix: stabilize test suite and repair frontend/backend wiring

- meshcore pin >=2.3.0 (EventType.STATS_CORE floor); setup.sh derives
  optional packages from requirements.txt; Python 3.10 warning
- agent-mode wifi clients proxy route + bare-array response handling
- remove dead AIS/ACARS/VDL2 SPA wiring and orphaned partials/CSS
- agent TLE download to data/tle/ (was littering repo root as gp.php)
- gate deferred background init off under pytest (mock-pollution race)
- complete Popen mocks (context manager protocol, communicate tuples)
- real pipe fds in weather-sat decoder tests (fd 10/11 collision caused
  10s SQLite stalls); satellite tests no longer rewrite data/satellites.py
- register 'live' pytest marker, excluded by default
- update stale test assertions to current APIs

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

static/js/modes/wifi.js

@@ -1371,7 +1371,8 @@ const WiFiMode = (function() {
             const data = await response.json();
             // Handle agent response format (may be nested in 'result')
             const result = isAgentMode && data.result ? data.result : data;
-            const clientList = result.clients || [];
+            // /wifi/v2/clients returns a bare array; tolerate {clients: [...]} too
+            const clientList = Array.isArray(result) ? result : (result.clients || []);
 
             if (clientList.length > 0) {
                 renderClientList(clientList, bssid);