feat(installers): chain codex install + ps1 fallback includes gpt-5.5

User reported on Mac/Win:
1. gpt-5.5 not appearing in client model picker after install
2. codex CLI not installed by uclaude_install.{sh,ps1}

Root causes (TDD verified):
1. ps1 hardcoded fallback (when private config fetch fails) had only 5
   models without gpt-5.5; users behind firewall/with stale cache fall
   back to it. Updated fallback to include latest list including gpt-5.5,
   gemini-3.1-pro, gemini-3-flash, glm-5.1.
2. Codex has SEPARATE installer (codex/ucodex_install.{sh,ps1}). Users
   following claude install instructions miss it. README documents both
   but as separate steps. Now uclaude_install.{sh,ps1} optionally chain
   to codex installer at the end (skip via UCLAUDE_SKIP_CODEX=1).

Sh installer: also expanded sparse-checkout to include codex/ directory.

README versions: bumped Codex CLI 0.122.0 → 0.125.0 in all 4 locale files
(README.md, README_ru.md, README_es.md, README_zh.md).

3 new tests in claude_code_patcher/tests/test_installers_completeness.py
verify the fix sticks (ps1 fallback has gpt-5.5, both installers mention
codex chain, README codex version current via GitHub API check).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

README_es.md

@@ -9,7 +9,7 @@ Herramientas de IA para codificación con soporte para puntos finales de API per
 | Carpeta | Herramienta | Estado |
 |-------|-----------|--------|
 | [claude/](claude/) | Claude Code | Activo (v2.1.112) |
-| [codex/](codex/) | OpenAI Codex CLI | **Activo (v0.122.0)** |
+| [codex/](codex/) | OpenAI Codex CLI | **Activo (v0.125.0)** |
 | [gemini/](gemini/) | Gemini CLI | **Activo (v0.35.3)** |
 | [qwen/](qwen/) | Qwen Code | **Activo (v0.14.5)** |
 | antigravity/ | Antigravity | Planeado |