feat(core): edit icon in navigation panel (#13595)

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

- **New Features**
- Rename dialog now edits per-item explorer icons (emoji or custom) and
can skip name-change callbacks. Doc icon picker added to the editor with
localized "Add icon" placeholder and readonly rendering. Icon editor
supports fallbacks, trigger variants, and improved input/test-id wiring.

- **Style**
- Updated icon picker and trigger sizing and placeholder visuals;
title/icon layout adjustments.

- **Chores**
- Explorer icon storage and module added to persist and serve icons
across the app.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/core/src/modules/db/schema/schema.ts

@@ -46,6 +46,14 @@ export const AFFiNE_WORKSPACE_DB_SCHEMA = {
     collectionId: f.string().primaryKey(),
     index: f.string(),
   },
+  explorerIcon: {
+    /**
+     * ${doc|collection|folder|tag}:${id}
+     */
+    id: f.string().primaryKey(),
+    type: f.enum('emoji', 'affine-icon', 'blob'),
+    icon: f.string(),
+  },
 } as const satisfies DBSchemaBuilder;
 export type AFFiNEWorkspaceDbSchema = typeof AFFiNE_WORKSPACE_DB_SCHEMA;
 
@@ -53,6 +61,10 @@ export type DocProperties = ORMEntity<AFFiNEWorkspaceDbSchema['docProperties']>;
 export type DocCustomPropertyInfo = ORMEntity<
   AFFiNEWorkspaceDbSchema['docCustomPropertyInfo']
 >;
+export type ExplorerIcon = ORMEntity<AFFiNEWorkspaceDbSchema['explorerIcon']>;
+export type ExplorerIconType = ORMEntity<
+  AFFiNEWorkspaceDbSchema['explorerIcon']
+>['type'];
 
 export const AFFiNE_WORKSPACE_USERDATA_DB_SCHEMA = {
   favorite: {