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>

setup.sh

@@ -230,7 +230,7 @@ case "$choice" in
     fi
 
     echo -e "${BLD}AI инструменты:${CLR}"
-    for cmd in ai-claude ai-gpt ai-deepseek ai-kimi ai-glm ai-openrouter ai-opencode ai-gemini android; do
+    for cmd in ai-claude ai-gpt ai-deepseek ai-kimi ai-glm ai-eltex ai-openrouter ai-opencode ai-gemini android; do
       if command -v "$cmd" &>/dev/null; then
         echo -e "  ${GRN}✓${CLR} $cmd"
       else
@@ -241,7 +241,7 @@ case "$choice" in
     echo ""
     echo -e "${BLD}API ключи:${CLR}"
     cfg="$HOME/.config/ai-setup"
-    for f in deepseek_key kimi_key glm_key openrouter_key opencode_key; do
+    for f in deepseek_key kimi_key glm_key eltex_key openrouter_key opencode_key; do
       name="${f/_key/}"
       if [ -s "$cfg/$f" ]; then
         echo -e "  ${GRN}✓${CLR} $name"