Complete Story 3.3: Preset Import & Export

Implements FR-19: Preset import/export as JSON

New Files:
- src/core/PresetImportExportManager.js - Core logic for export/import with merge/replace
- src/ui/gm/PresetExportDialog.js - Export dialog with file download
- src/ui/gm/PresetImportDialog.js - Import dialog with file picker, preview, merge/replace
- templates/preset-export.hbs - Export dialog template
- templates/preset-import.hbs - Import dialog template
- styles/components/_preset-import-export.less - Dialog styles
- tests/unit/core/PresetImportExportManager.test.js - 38 unit tests
- _bmad-output/implementation-artifacts/3-3-preset-import-and-export.md - Story file

Modified Files:
- src/ui/gm/DirectorsBoard.js - Added export/import button handlers
- templates/directors-board.hbs - Added Export/Import buttons to footer
- styles/scrying-pool.less - Added stylesheet import
- lang/en.json - Added localization strings for new UI
- _bmad-output/implementation-artifacts/sprint-status.yaml - Story status: review

Features:
- Export all presets from current scene as JSON file
- Import presets with merge (add new, skip duplicates) or replace (overwrite all) modes
- Preview of presets before import with validation status
- Confirmation dialog for replace mode to prevent data loss
- Comprehensive error handling and validation
- All ACs satisfied (AC-9 deferred for README docs)

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

templates/preset-import.hbs

@@ -0,0 +1,90 @@
+<div class="sp-dialog-content">
+  <p class="sp-import-description">
+    {{localize "SCRYING_POOL.ImportPresetsDescription"}}
+  </p>
+
+  {{#if hasExistingPresets}}
+  <div class="sp-warning-box">
+    <i class="fas fa-exclamation-triangle"></i>
+    <span>{{localize "SCRYING_POOL.ExistingPresetsWarning" existingPresetCount=existingPresetCount}}</span>
+  </div>
+  {{/if}}
+
+  {{!-- File Selection --}}
+  <div class="sp-form-group">
+    <label class="sp-form-label">{{localize "SCRYING_POOL.SelectFile"}}</label>
+    <div class="sp-file-upload">
+      <input type="file" class="sp-file-input" accept=".json" />
+      <label class="sp-file-label">
+        <i class="fas fa-upload"></i>
+        <span class="sp-file-text">{{localize "SCRYING_POOL.ChooseFile"}}</span>
+      </label>
+    </div>
+    {{#if selectedFileName}}
+    <div class="sp-file-selected">
+      <i class="fas fa-check-circle"></i>
+      <span>{{selectedFileName}}</span>
+    </div>
+    {{/if}}
+  </div>
+
+  {{!-- Mode Selection --}}
+  <div class="sp-form-group">
+    <label class="sp-form-label">{{localize "SCRYING_POOL.ImportMode"}}</label>
+    <div class="sp-radio-group">
+      <label class="sp-radio-label">
+        <input type="radio" name="import-mode" class="sp-mode-merge" value="merge" {{checked (eq mode "merge")}} />
+        <span class="sp-radio-text">{{mergeLabel}}</span>
+        <span class="sp-radio-hint">{{localize "SCRYING_POOL.ImportModeMergeHint"}}</span>
+      </label>
+      <label class="sp-radio-label">
+        <input type="radio" name="import-mode" class="sp-mode-replace" value="replace" {{checked (eq mode "replace")}} />
+        <span class="sp-radio-text">{{replaceLabel}}</span>
+        <span class="sp-radio-hint">{{localize "SCRYING_POOL.ImportModeReplaceHint"}}</span>
+      </label>
+    </div>
+  </div>
+
+  {{!-- Preview Section --}}
+  {{#if previewItems.length}}
+  <div class="sp-preview-section">
+    <h3 class="sp-preview-title">{{localize "SCRYING_POOL.PreviewTitle"}}</h3>
+    <ul class="sp-preview-list">
+      {{#each previewItems as |item|}}
+      <li class="sp-preview-item {{unless item.valid 'sp-preview-item--invalid'}}">
+        <i class="fas {{if item.valid 'fa-check-circle sp-valid' 'fa-exclamation-circle sp-invalid'}}"></i>
+        <span class="sp-preview-name">{{item.name}}</span>
+        {{#if item.error}}
+        <span class="sp-preview-error" title="{{item.error}}">{{item.error}}</span>
+        {{/if}}
+      </li>
+      {{/each}}
+    </ul>
+  </div>
+  {{/if}}
+
+  {{!-- Confirmation Section (shown for replace mode) --}}
+  {{#if requiresConfirmation}}
+  <div class="sp-confirmation-section">
+    <div class="sp-confirmation-warning">
+      <i class="fas fa-exclamation-triangle"></i>
+      <span>{{localize "SCRYING_POOL.ReplaceConfirmation" existingPresetCount=existingPresetCount}}</span>
+    </div>
+  </div>
+  {{/if}}
+</div>
+
+<div class="sp-dialog-buttons">
+  {{#unless requiresConfirmation}}
+  <button type="button" class="sp-btn sp-btn-primary sp-import-btn" {{disabled (not previewItems.length) }}>
+    <i class="fas fa-file-import"></i> {{localize "SCRYING_POOL.Import"}}
+  </button>
+  {{else}}
+  <button type="button" class="sp-btn sp-btn-danger sp-confirm-btn">
+    <i class="fas fa-check"></i> {{localize "SCRYING_POOL.ConfirmReplace"}}
+  </button>
+  {{/unless}}
+  <button type="button" class="sp-btn sp-btn-secondary sp-cancel-btn">
+    {{localize "SCRYING_POOL.Cancel"}}
+  </button>
+</div>