docs(readme): drop Paper feature, simplify gallery, add scripts inventory

Major restructure:
- Remove Paper feature entirely (IPaperSurface, PaperSurface, PaperSurfaceModule).
  Paper is just RectTransforms in the ColorBook scene, exposed via a
  ColorBookSceneRefs MonoBehaviour the scope registers as a singleton.
- Simplify IGalleryService to a single SaveToDeviceAsync(byte[], albumName)
  shim over a native gallery plugin. Drop ListAsync / LoadFullAsync /
  LoadThumbnailAsync / DeleteAsync / GetLatestThumbnailAsync /
  SavedArtworkDTO / sidecar JSON / persistentDataPath gallery folder.
- Drop ArtBook feature (no in-app gallery — users view captures in phone
  Photos). Removes ArtBookLifetimeScope, GalleryPresenter, IExternalShareService.
- Replace ArtworkCapturedSignal / ArtworkSavedSignal with PaperCapturedSignal /
  PaperSavedSignal (templateId only).
- Capture and Gallery are now independent: ICaptureService produces PNG bytes,
  IGalleryService writes them to native Photos. CaptureController orchestrates
  the chain.
- Rewrite §11 Persistence — only ProtectedPlayerPrefs for settings/progression;
  no app-side image store.
- Remove §28 SavedArtwork JSON Schema; replace with §28 Native Gallery
  Integration (plugin recommendations, permission flows).
- Add §31b: Scripts Inventory by Domain — comprehensive path-by-path table
  of every script (existing and planned) across Core / Libs / Services /
  Features / App, with status markers.
- Update Readme.docx — better formatting (page break before each numbered
  section, blue heading underlines, alternating row shading on tables,
  monospace code blocks with left accent bar, expanded title page).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Assets/Darkmatter/Code/Services/Gallery/Core/GalleryService.cs

@@ -1,3 +1,5 @@
+using System;
+using Cysharp.Threading.Tasks;
 using Darkmatter.Core.Contracts.Services.Gallery;
 using UnityEngine;
 
@@ -5,9 +7,33 @@ namespace Darkmatter.Services.Gallery
 {
     public class GalleryService : IGalleryService
     {
-        public void SaveImageAsync(Texture2D image, string fileName)
+        public async UniTask SaveImageAsync(Texture2D image, string fileName, string albumName = "Colorbook")
         {
-            NativeGallery.SaveImageToGallery(image, "ColorBook", fileName);
+            var permission = await NativeGallery.RequestPermissionAsync(NativeGallery.PermissionType.Write,
+                NativeGallery.MediaType.Image);
+
+            if (permission != NativeGallery.Permission.Granted)
+            {
+                return;
+            }
+
+            var tcs = new UniTaskCompletionSource();
+
+            NativeGallery.SaveImageToGallery(image, albumName,
+                filename: $"colorbook_{DateTime.UtcNow:yyyyMMdd_HHmmss}.png", callback: (success, path) =>
+                {
+                    if (!success)
+                    {
+                        Debug.LogError("Failed to save image to gallery.");
+                    }
+                    else
+                    {
+                        Debug.Log($"Image saved to gallery at: {path}");
+                    }
+                    tcs.TrySetResult();
+                });
+
+            await tcs.Task;
         }
     }
 }