chore: commit remaining working changes

Backend:
- agent: confirmation, persistence, app, langgraph_setup updates
- routes: agent_superset_explore, environments, git helpers/operations
- services: git sync refactoring
- tests: git_status_route expanded

Frontend:
- Navbar: minor cleanup
- Profile: i18n (en/ru), page enhancements, integration tests
- New: _llm_params.py

backend/src/agent/_llm_params.py

@@ -0,0 +1,70 @@
+# backend/src/agent/_llm_params.py
+# #region AgentChat.LlmParams [C:3] [TYPE Module] [SEMANTICS agent-chat,llm,openai,compatibility]
+# @defgroup AgentChat Shared LLM parameter compatibility helpers.
+# @LAYER Service
+# @BRIEF Build provider-safe ChatOpenAI kwargs and raw OpenAI payloads.
+# @POST Unsupported sampling parameters are omitted for reasoning/codex models.
+# @RATIONALE Some OpenAI-compatible gateways reject temperature for reasoning/codex
+#            models. Centralising the guard prevents resume, health-check, and title
+#            generation paths from diverging.
+
+from typing import Any
+
+
+_TEMPERATURE_UNSUPPORTED_PREFIXES = (
+    "codex/",
+    "omni/codex/",
+    "gpt-5",
+    "o1",
+    "o3",
+    "o4",
+)
+
+
+def _canonical_model_name(model: str | None) -> str:
+    """Return provider-stripped, lowercase model name for compatibility checks."""
+    name = (model or "").strip().lower()
+    if name.startswith(("codex/", "omni/codex/")):
+        return name
+    if "/" in name:
+        return name.rsplit("/", 1)[-1]
+    return name
+
+
+def supports_temperature(model: str | None) -> bool:
+    """Return False for model families whose APIs reject temperature."""
+    name = _canonical_model_name(model)
+    return not any(name.startswith(prefix) for prefix in _TEMPERATURE_UNSUPPORTED_PREFIXES)
+
+
+def chat_openai_kwargs(
+    *,
+    model: str,
+    base_url: str | None,
+    api_key: str,
+    max_tokens: int,
+    temperature: float = 0,
+) -> dict[str, Any]:
+    """Build ChatOpenAI kwargs without unsupported temperature for reasoning models."""
+    kwargs: dict[str, Any] = {
+        "model": model,
+        "base_url": base_url,
+        "api_key": api_key,
+        "max_tokens": max_tokens,
+    }
+    if supports_temperature(model):
+        kwargs["temperature"] = temperature
+    return kwargs
+
+
+def add_temperature_if_supported(
+    payload: dict[str, Any],
+    *,
+    model: str | None,
+    temperature: float = 0,
+) -> dict[str, Any]:
+    """Mutate and return payload with temperature only when the model supports it."""
+    if supports_temperature(model):
+        payload["temperature"] = temperature
+    return payload
+# #endregion AgentChat.LlmParams