Replace individual Envea sensor cards with single debug card

Modified the sensors page to display a unified debug view for all Envea gas sensors:

Backend changes:
- Added new 'envea_debug' endpoint in launcher.php
- Calls: /usr/bin/python3 /var/www/nebuleair_pro_4g/envea/read_value_v2.py -d
- Returns raw debug output without parsing

Frontend changes:
- Replaced individual sensor cards with single combined card
- Card displays if any gas sensor is connected
- Shows list of connected sensors (NO2, H2S, NH3, etc.)
- New getENVEA_debug_values() function fetches debug data
- Raw output displayed in scrollable <pre> block
- No JSON parsing, no table formatting - just raw debug text
- Card width set to col-sm-6 for better visibility

This makes it easier to check if all sensors are working correctly by viewing the raw output.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

html/launcher.php

@@ -569,6 +569,12 @@ if ($type == "envea") {
     echo $output;
 }
 
+if ($type == "envea_debug") {
+    $command = 'sudo /usr/bin/python3 /var/www/nebuleair_pro_4g/envea/read_value_v2.py -d 2>&1';
+    $output = shell_exec($command);
+    echo $output;
+}
+
 if ($type == "noise") {
     $command = '/var/www/nebuleair_pro_4g/sound_meter/sound_meter';
     $output = shell_exec($command);