Streamline calibration modal: inline controls, dynamic aspect ratio, offset fix

- Move total LEDs counter, direction toggle, and offset input into the
  screen area of the calibration preview
- Remove description paragraph, standalone offset form, and total LEDs banner
- Add mismatch warning (yellow + ⚠) when configured LEDs ≠ device count
- Use actual display aspect ratio for calibration preview
- Fix offset not updating tick labels (buildSegments now starts at offset)
- Remove max-width constraint on preview, add padding for breathing room
- Clean up unused i18n keys from both locale files

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/wled_controller/static/index.html

@@ -83,19 +83,21 @@
             </div>
             <div class="modal-body">
                 <input type="hidden" id="calibration-device-id">
-                <p style="margin-bottom: 12px; color: var(--text-secondary);" data-i18n="calibration.description">
-                    Configure how your LED strip is mapped to screen edges. Click an edge to toggle test mode.
-                </p>
-
                 <!-- Interactive Preview with integrated LED inputs and test toggles -->
-                <div style="margin-bottom: 12px;">
+                <div style="margin-bottom: 12px; padding: 0 24px;">
                     <div class="calibration-preview">
-                        <!-- Screen with direction toggle -->
+                        <!-- Screen with direction toggle, total LEDs, and offset -->
                         <div class="preview-screen">
-                            <span data-i18n="calibration.preview.screen">Screen</span>
-                            <button type="button" class="direction-toggle" onclick="toggleDirection()" title="Toggle direction">
-                                <span id="direction-icon">↻</span> <span id="direction-label">CW</span>
-                            </button>
+                            <div class="preview-screen-total"><span id="cal-total-leds-inline">0</span> / <span id="cal-device-led-count-inline">0</span></div>
+                            <div class="preview-screen-controls">
+                                <button type="button" class="direction-toggle" onclick="toggleDirection()" title="Toggle direction">
+                                    <span id="direction-icon">↻</span> <span id="direction-label">CW</span>
+                                </button>
+                                <label class="offset-control" title="LED offset from LED 0 to start corner">
+                                    <span>⊕</span>
+                                    <input type="number" id="cal-offset" min="0" value="0" oninput="updateCalibrationPreview()">
+                                </label>
+                            </div>
                         </div>
 
                         <!-- Clickable edge bars with LED count inputs -->
@@ -142,15 +144,6 @@
                     </select>
                 </div>
 
-                <div class="form-group" style="margin-bottom: 12px;">
-                    <label for="cal-offset" data-i18n="calibration.offset">LED Offset:</label>
-                    <input type="number" id="cal-offset" min="0" value="0" oninput="updateCalibrationPreview()">
-                    <small style="color: #aaa; display: block; margin-top: 4px;" data-i18n="calibration.offset_hint">LEDs from LED 0 to start corner (along strip)</small>
-                </div>
-
-                <div style="padding: 8px 10px; background: rgba(255, 193, 7, 0.1); border-left: 4px solid #FFC107; border-radius: 4px; margin-bottom: 12px;">
-                    <strong data-i18n="calibration.total">Total LEDs:</strong> <span id="cal-total-leds">0</span> / <span id="cal-device-led-count">0</span>
-                </div>
 
                 <div id="calibration-error" class="error-message" style="display: none;"></div>
             </div>