chore: bump version to 0.2.13

[wgqqqqq]

Summary

• bump BitFun product versions from 0.2.12 to 0.2.13
• keep desktop, web, mobile web, relay server, and installer version metadata aligned
• update version display fallbacks and the announcement request contract fixture

Verification

• pnpm run type-check:web
• pnpm --dir src/mobile-web run type-check
• pnpm --dir BitFun-Installer run type-check
• cargo check --workspace
• cargo check --manifest-path BitFun-Installer/src-tauri/Cargo.toml
• cargo test -p bitfun-services-integrations --features announcement --test announcement_contracts announcement_remote_fetch_request_preserves_legacy_query_shape -- --exact
• pnpm run check:repo-hygiene
• pnpm run check:github-config
• git diff --check

AI-assisted: Yes (Codex)
Testing level: Fully tested for the changed scope.