feat(eltex): add ai-eltex launcher for corporate LLM proxy

ai-eltex runs Claude Code through the Eltex LiteLLM proxy
(http://llm.eltex.loc:4000, team GLM subscription). The personal key
from admins is checked via /v1/models and stored in
~/.config/ai-setup/eltex_key; the model is taken from the key's
allowed list (ELTEX_MODEL / ELTEX_BASE_URL override). The proxy
ignores effort/thinking, so no effort forcing. /logout-eltex and
/logout in ai-eltex drop the key; setup.sh status shows it.

ru-bypass: hosts block now has an end marker and only that block is
rewritten, manual entries outside it survive; llm.eltex.loc/llm2 added
since the VPN DNS does not resolve it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

QUICK_START.md

@@ -7,7 +7,7 @@ bash setup.sh
 ```
 
 Установит лаунчеры
-`ai-claude`, `ai-gpt`, `ai-deepseek`, `ai-kimi`, `ai-glm`, `ai-openrouter`, `ai-opencode`, `ai-gemini`, `ai-cursor`
+`ai-claude`, `ai-gpt`, `ai-deepseek`, `ai-kimi`, `ai-glm`, `ai-eltex`, `ai-openrouter`, `ai-opencode`, `ai-gemini`, `ai-cursor`
 в `~/bin`, если он уже есть в `PATH`, иначе в `~/.local/bin/`, и запишет API-ключи.
 
 После установки, если команды не видны: