feat(automations): implement model eligibility checks for automation creation

- Added model eligibility checks to ensure automations can only use billable models (premium or BYOK).
- Introduced new API endpoint to report model eligibility status for search spaces.
- Updated frontend components to display eligibility alerts and disable creation options when models are not billable.
- Enhanced automation creation forms to reflect model eligibility, preventing users from submitting invalid configurations.
- Implemented server-side logic to capture and preserve model preferences across automation edits, ensuring consistent behavior during execution.

surfsense_backend/tests/unit/automations/runtime/test_executor_action_ctx.py

@@ -0,0 +1,59 @@
+"""Lock that the executor propagates the captured model snapshot into the
+``ActionContext``, so runs resolve their own model (insulated from chat /
+search-space changes) and not the live search space.
+"""
+
+from __future__ import annotations
+
+from types import SimpleNamespace
+from typing import cast
+
+import pytest
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.automations.runtime.executor import _build_action_ctx
+from app.automations.schemas.definition.envelope import AutomationModels
+from app.automations.schemas.definition.plan_step import PlanStep
+
+pytestmark = pytest.mark.unit
+
+
+def _run() -> SimpleNamespace:
+    return SimpleNamespace(
+        id=1,
+        automation=SimpleNamespace(search_space_id=42, created_by_user_id="u-1"),
+    )
+
+
+def test_build_action_ctx_propagates_captured_models() -> None:
+    """``definition.models`` flows onto the ActionContext model fields."""
+    models = AutomationModels(
+        agent_llm_id=-1,
+        image_generation_config_id=5,
+        vision_llm_config_id=-1,
+    )
+    ctx = _build_action_ctx(
+        cast(AsyncSession, None),
+        _run(),
+        PlanStep(step_id="s1", action="agent_task"),
+        models,
+    )
+
+    assert ctx.search_space_id == 42
+    assert ctx.agent_llm_id == -1
+    assert ctx.image_generation_config_id == 5
+    assert ctx.vision_llm_config_id == -1
+
+
+def test_build_action_ctx_none_models_leaves_fields_none() -> None:
+    """No captured snapshot → model fields are None (defensive fallback path)."""
+    ctx = _build_action_ctx(
+        cast(AsyncSession, None),
+        _run(),
+        PlanStep(step_id="s1", action="agent_task"),
+        None,
+    )
+
+    assert ctx.agent_llm_id is None
+    assert ctx.image_generation_config_id is None
+    assert ctx.vision_llm_config_id is None