feat(ui): searchable model picker with provider group headers — v0.50.86 (PR #659 by @mmartial)

- Live search input in model dropdown (filter by name or ID)
- Provider group headers preserved in filtered view
- Clear button, Escape-to-close, No models found empty state
- i18n EN/ES/zh-CN strings
- CSS uses var(--accent) consistent with current theme system
- zh-CN double-escape fix included
- Provider headers regression fix included
- 1423 tests pass

Co-authored-by: mmartial <mmartial@users.noreply.github.com>

CHANGELOG.md

@@ -1,6 +1,11 @@
 # Hermes Web UI -- Changelog
 
-## [v0.50.85] — 2026-04-18
+## [v0.50.86] — 2026-04-18
+
+### Added
+- **Searchable model picker** — the model dropdown now has a live search input at the top. Type any part of a model name or ID to filter the list instantly; provider group headers (Anthropic, OpenAI, OpenRouter, etc.) remain visible in filtered results. Includes a clear button, Escape-to-close support, and a "No models found" empty state. i18n strings added for English, Spanish, and zh-CN. (PR #659 by @mmartial)
+
+
 
 ### Fixed
 - **`_provider_oauth_authenticated()` now respects the `hermes_home` parameter** — the function had a CLI fast path (`hermes_cli.auth.get_auth_status()`) that ignored the caller-supplied `hermes_home` and read from the real system home. On machines where `openai-codex` (or another OAuth provider) was genuinely authenticated, this caused three test assertions to return `True` instead of `False`, regardless of the isolated `tmp_path` the test passed in. Removed the CLI fast path; the function now reads exclusively from `hermes_home/auth.json`, which is both the correct scoped behavior and what the docstring described. No functional change for production (the auth.json path was already the complete fallback). (Fixes pre-existing test_sprint34 failures)