refactor(db): consolidate BOARD_READER_ID in helpers + escape backslash in LIKE (P3-50, P1-26)

src/main/database/snapshot.ts

@@ -15,8 +15,7 @@ import type {
   TaskRecord,
   WorkspaceRecord,
 } from "@shared/types";
-import { type ReadAll, type SqliteRow, toBoolean } from "./helpers";
-const BOARD_READER_ID = "__board__";
+import { BOARD_READER_ID, type ReadAll, type SqliteRow, toBoolean } from "./helpers";
 
 export function buildSnapshotMethods(
   getDb: () => DatabaseSync,