refactor(review): address #230 third review — callout dedup, ticket/type tidy

Approve-with-comments follow-ups (no blockers):

- callout: unify the GitHub-callout feature ticket on #192 (the callout-paste
  feature the CHANGELOG already tracks); #218 is the public-share security work.
  Fixed the code comment and test reference.
- export/utils.spec: pin current behavior of a leading-dot name (".gitignore" ->
  "") — same bug class as #204 but unreachable via the sole caller, so document
  not change.
- share.types: narrow ISharedPage to the actual /shares/page-info allowlist
  (page -> Pick of id/slugId/title/icon/content; trimmed share; dropped the
  spurious `extends IShare`). Verified all three consumers (shared-page,
  link-view, mention-view) read only allowlist fields.
- editor-ext: extract shared CALLOUT_TYPES / normalizeCalloutType /
  renderCalloutHtml into callout-common.marked.ts; both tokenizers
  (`:::type` and `> [!type]`) now share the renderer + type dict while staying
  separate. Eliminates the byte-identical renderer + duplicated type list.
- share.service: extract named predicate shareIdGrantsAccess(requestedShareId,
  resolvedShare) for the id-or-key fast path (naming only, no control-flow
  change); kept narrower than resolveReadableSharePage's id-only gate.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/client/src/features/share/types/share.types.ts

@@ -35,9 +35,17 @@ export interface ISharedItem extends IShare {
   };
 }
 
-export interface ISharedPage extends IShare {
-  page: IPage;
-  share: IShare & {
+// The `/shares/page-info` (anonymous) response. Mirrors the server-side
+// PublicSharePayload allowlist (#218): the server trims `page`/`share` to these
+// fields exactly, so the client type must not over-declare internal metadata it
+// will never receive. Keep this in sync with share-public-payload.ts.
+export interface ISharedPage {
+  page: Pick<IPage, "id" | "slugId" | "title" | "icon" | "content">;
+  share: {
+    id: string;
+    key: string;
+    includeSubPages: boolean;
+    searchIndexing: boolean;
     level: number;
     sharedPage: { id: string; slugId: string; title: string; icon: string };
   };