fix(installer): retry git ops + reject placeholder api_key + sync public configs

User hit two bugs in production:
1. uclaude_install.sh ERROR: Command failed at line 82 — gitea returned
   transient HTTP 502 to `git fetch`, `2>/dev/null` masked stderr but
   ERR trap fired with cryptic message.
2. After install, claude model picker showed only 5 models (built-in
   defaults) instead of 19. Root cause: load_config() fell back to the
   PUBLIC sanitized patcher.config.json (api_key='YOUR_API_KEY') after
   remote fetch failed → claude API auth broken → custom models invisible.

Fixes:

claude/uclaude_install.sh:
- New retry_git() helper: 3 attempts, 5s backoff, loud diagnostic
- Existing-clone branch: retry_git wraps `git fetch` AND `git reset`
- Fallback: if fetch fails 3x on existing clone, nuke and re-clone fresh
  (incremental fetch breaks more often than full clone on flaky gitea)
- Secondary fetch (before updater): tolerates failure with `|| true`
  (we already have a working clone)

claude/uclaude_updater.py:
- _config_is_usable() guard: rejects {"api_key": "YOUR_API_KEY"} etc.
- load_config() retries remote 3x with backoff before falling back
- Removed local-file fallback (was loading public sanitized = bait)
- Cache-only fallback now (from previous successful fetch)

Public configs synced from canonical (api_key sanitized, models list
fully refreshed):
- claude/patcher.config.json: 17 → 19 models (+gpt-5.5, +gemini-3.1-pro etc)
- codex/codex_config.json: 4 → 5 models (+gpt-5.5)
- gemini/gemini_config.json: refreshed
- target_version: 2.1.112 → 2.1.119

Tests: tests/test_installer_robustness.py — 6 new GREEN guards.
Total: 196 → 207 GREEN.

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

claude/patcher.config.json

@@ -9,14 +9,16 @@
     "claude-haiku-4-5-20251001",
     "claude-opus-4-5-20251101",
     "claude-sonnet-4-5-20250929",
+    "gpt-5.5",
     "gpt-5.4",
     "gpt-5.4-mini",
     "gpt-5.3-codex",
-    "gemini-3-pro-preview",
+    "gemini-3.1-pro",
+    "gemini-3.1-pro-preview",
+    "gemini-3.1-pro-preview-customtools",
+    "gemini-3-flash",
     "gemini-3-flash-preview",
-    "qwen3-coder-plus",
-    "qwen3-coder-flash",
-    "qwen3.5-coder-plus",
+    "gemini-2.5-flash",
     "glm-5.1",
     "glm-5",
     "glm-4.7"
@@ -26,7 +28,7 @@
   "timeout_ms": 3000000,
   "theme": "dark",
   "complete_onboarding": true,
-  "target_version": "2.1.112",
+  "target_version": "2.1.119",
   "effort_level": "high",
   "_note": "Production api_key lives in PRIVATE unlimitedcoding-config repo. uclaude_updater.py fetches it at runtime with token auth."
 }