feat(core): support Notion markdown zip imports (#14910)

## What changed
- Markdown zip imports now resolve local `.md` links like `./test/2.md`
into AFFiNE linked-page references when the target document exists in
the same archive.
- Added Notion Markdown `.zip` import support in the desktop import
dialog, including nested zip traversal, Notion title extraction,
hash-stripped folder names, attachments, and folder hierarchy
integration.
- Added i18n entries and adapter coverage for standard Markdown zip
links and Notion Markdown zip imports.

## Why
Markdown and Notion exports often contain links between notes using
relative `.md` paths. Keeping those as plain URLs makes imported
workspaces harder to navigate, so the importer now preassigns document
ids and rewrites resolvable archive-local markdown links into linked
pages.

## Notes
The markdown zip folder hierarchy implementation now comes from latest
`origin/canary`, so this PR only layers relative-link resolution and
Notion Markdown zip support on top of that upstream behavior.

## Validation
- `yarn vitest --run
blocksuite/affine/all/src/__tests__/adapters/markdown.unit.spec.ts`
- `yarn tsc -b blocksuite/affine/all/tsconfig.json --verbose`
- `git diff --check`

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* Added support for importing Notion Markdown exports in `.zip` format,
including subpages, attachments, and nested folders.
* Internal links inside imported Markdown now resolve correctly between
pages, preserving link text when available.
* The import dialog now includes a dedicated “Notion (Markdown, .zip)”
option.

* **Bug Fixes**
* Improved filename handling so non-Latin characters in ZIP imports are
preserved correctly.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Co-authored-by: DarkSky <25152247+darkskygit@users.noreply.github.com>
Co-authored-by: DarkSky <darksky2048@gmail.com>

packages/frontend/core/src/desktop/dialogs/import/index.tsx

@@ -231,6 +231,7 @@ type ImportType =
   | 'markdown'
   | 'markdownZip'
   | 'notion'
+  | 'notionMarkdown'
   | 'obsidian'
   | 'bear'
   | 'snapshot'
@@ -318,6 +319,17 @@ const importOptions = [
     testId: 'editor-option-menu-import-notion',
     type: 'notion' as ImportType,
   },
+  {
+    key: 'notionMarkdown',
+    label: 'com.affine.import.notion-markdown',
+    prefixIcon: <NotionIcon color={cssVar('black')} width={20} height={20} />,
+    suffixIcon: (
+      <HelpIcon color={cssVarV2('icon/primary')} width={20} height={20} />
+    ),
+    suffixTooltip: 'com.affine.import.notion-markdown.tooltip',
+    testId: 'editor-option-menu-import-notion-markdown',
+    type: 'notionMarkdown' as ImportType,
+  },
   {
     key: 'obsidian',
     label: 'com.affine.import.obsidian',
@@ -510,6 +522,42 @@ const importConfigs: Record<ImportType, ImportConfig> = {
       };
     },
   },
+  notionMarkdown: {
+    fileOptions: { acceptType: 'Zip', multiple: false },
+    importFunction: async (
+      docCollection,
+      files,
+      _handleImportAffineFile,
+      organizeService,
+      explorerIconService
+    ) => {
+      const file = files.length === 1 ? files[0] : null;
+      if (!file) {
+        throw new Error('Expected a single zip file for notionMarkdown import');
+      }
+      const { docIds, folderHierarchy } =
+        await MarkdownTransformer.importNotionMarkdownZip({
+          collection: docCollection,
+          schema: getAFFiNEWorkspaceSchema(),
+          imported: file,
+          extensions: getStoreManager().config.init().value.get('store'),
+        });
+
+      const rootFolderId =
+        folderHierarchy && organizeService
+          ? applyFolderHierarchy(
+              organizeService,
+              folderHierarchy,
+              explorerIconService
+            )
+          : undefined;
+
+      return {
+        docIds,
+        rootFolderId,
+      };
+    },
+  },
   obsidian: {
     fileOptions: { acceptType: 'Directory', multiple: false },
     importFunction: async (