Fix SpoolBuddy scale tare & calibration not being applied

The tare and calibrate buttons on the Settings page queued commands
  but never executed them due to five broken links:

  1. Daemon received tare command but never called scale.tare()
  2. No endpoint to persist tare offset back to backend DB
  3. Heartbeat never called scale.update_calibration()
  4. Heartbeat response with stale values overwrote new tare to zero
  5. set-factor used DB tare_offset (stale/zero), producing wrong
     calibration factor — empty scale showed ~5000g

  Fixed daemon to execute tare, persist result, and propagate
  calibration. Calibration step now captures raw ADC at tare time
  and sends it with step 2, making factor computation self-contained.

  Replaced calibration weight input with compact touch numpad for
  the RPi kiosk's 1024x600 touchscreen (no physical keyboard).

static/index.html

@@ -23,8 +23,8 @@
 
     <!-- Splash screens for iOS -->
     <link rel="apple-touch-startup-image" href="/img/android-chrome-512x512.png" />
-    <script type="module" crossorigin src="/assets/index-C-1HSQvy.js"></script>
-    <link rel="stylesheet" crossorigin href="/assets/index-BnyNVaG5.css">
+    <script type="module" crossorigin src="/assets/index-D_O4r8aB.js"></script>
+    <link rel="stylesheet" crossorigin href="/assets/index-BW78djlt.css">
   </head>
   <body>
     <div id="root"></div>