Add Shift+C microphone input calibration

client/public/help.json

@@ -129,8 +129,12 @@
         {
           "keys": "Dash or Equals",
           "description": "Lower/raise active effect value"
+        },
+        {
+          "keys": "Shift+C",
+          "description": "Calibrate mic input gain over 5 seconds"
         }
       ]
     }
   ]
-}
+}

client/public/version.js

@@ -1,5 +1,5 @@
 // Maintainer-controlled web client version.
 // Format: YYYY.MM.DD Rn (example: 2026.02.20 R2)
-window.CHGRID_WEB_VERSION = "2026.02.22 R147";
+window.CHGRID_WEB_VERSION = "2026.02.22 R148";
 // Optional display timezone for timestamps. Falls back to America/Detroit if unset/invalid.
 window.CHGRID_TIME_ZONE = "America/Detroit";