Made the top-left space identity read as a switcher without changing its existing interaction:
- added a persistent, non-shrinking trailing chevron and long-name-safe truncation;
- exposed an action-oriented accessible name, dialog popup type, and expanded state;
- gave the overlay picker dialog semantics while leaving the standalone picker as page content;
- added a visible keyboard-focus treatment and a focused contract test for the affordance and semantics.
Checks passed: pnpm --filter @radial/ui test (87 Node tests and 811 Vitest tests), pnpm build, pnpm typecheck, pnpm lint, git diff --check, and the Impeccable detector (no findings). The build used the repository's supported no-browser-WASM fallback because the optional generated binding was absent; this change does not touch private transport.
Branch: radial/impl-22d5df36f4a0
Commit: 73bc31e0cc0369786b137faecc4c1ed5a341305d