Restructure ORA editor into modular blueprints with browse dialog

- Split app.py into route blueprints (files, layers, images, polygon, mask, krita)
- Create services layer (polygon_storage, comfyui, file_browser)
- Extract config constants to config.py
- Split templates into Jinja partials (base, components, modals)
- Add browse dialog for visual file navigation
- Add /api/browse endpoint for directory listing

tools/ora_editor/templates/modals/mask_preview.html

@@ -0,0 +1,49 @@
+<!-- Mask preview modal for ORA Editor -->
+
+<div x-show="showMaskModal" @keydown.escape.window="closeMaskModal()" 
+     class="fixed inset-0 z-50 flex items-center justify-center bg-black bg-opacity-75">
+    <div class="bg-gray-800 rounded-lg p-6 max-w-2xl w-full mx-4 border border-gray-600" style="max-height: 90vh; display: flex; flex-direction: column;">
+        <div class="flex items-center justify-between mb-4">
+            <h2 class="text-xl font-bold">Extracted Mask</h2>
+            <!-- View mode toggle -->
+            <div class="flex gap-2">
+                <button 
+                    @click="maskViewMode = 'with-bg'"
+                    :class="maskViewMode === 'with-bg' ? 'bg-blue-600' : 'bg-gray-600'"
+                    class="px-3 py-1 rounded text-sm font-medium"
+                >With Background</button>
+                <button 
+                    @click="maskViewMode = 'masked-only'"
+                    :class="maskViewMode === 'masked-only' ? 'bg-green-600' : 'bg-gray-600'"
+                    class="px-3 py-1 rounded text-sm font-medium"
+                >Masked Only</button>
+            </div>
+        </div>
+        
+        <div class="flex-1 overflow-auto bg-gray-700 rounded mb-4 flex items-center justify-center p-4" style="min-height: 300px; max-height: 50vh;">
+            <div class="relative" style="max-width: 100%; max-height: calc(50vh - 2rem);">
+                <!-- Base image (shown in "with-bg" mode) -->
+                <img 
+                    x-show="maskViewMode === 'with-bg'"
+                    :src="'/api/image/base?ora_path=' + encodeURIComponent(oraPath)"
+                    class="border border-gray-600"
+                    style="max-width: 100%; max-height: calc(50vh - 2rem);"
+                >
+                <!-- Masked image (transparent where mask is black) -->
+                <img 
+                    x-show="tempMaskPath"
+                    :src="'/api/image/masked?ora_path=' + encodeURIComponent(oraPath) + '&mask_path=' + encodeURIComponent(tempMaskPath)"
+                    class="border border-gray-600"
+                    :class="maskViewMode === 'with-bg' ? 'absolute inset-0' : ''"
+                    style="max-width: 100%; max-height: calc(50vh - 2rem);"
+                >
+            </div>
+        </div>
+        
+        <div class="flex gap-4 justify-end">
+            <button @click="rerollMask()" :disabled="isExtracting" class="bg-gray-600 hover:bg-gray-500 disabled:bg-gray-700 px-4 py-2 rounded transition">Re-roll</button>
+            <button @click="useMask()" :disabled="isExtracting || !tempMaskPath" class="bg-green-600 hover:bg-green-700 disabled:bg-gray-600 px-4 py-2 rounded transition">Use This Mask</button>
+            <button @click="closeMaskModal()" :disabled="isExtracting" class="bg-red-600 hover:bg-red-700 disabled:bg-gray-600 px-4 py-2 rounded transition">Cancel</button>
+        </div>
+    </div>
+</div>