feat(api): add LLM model configurations endpoint and schemas

- Introduce new API route `/access` for managing LLM model configurations
- Add LLMModelConfig model to database models
- Include comprehensive schemas for LLM model config CRUD operations
- Register new router with tags for LLM Model Configurations

gns3server/schemas/controller/llm_model_configs.py

@@ -0,0 +1,102 @@
+#
+# Copyright (C) 2026 GNS3 Technologies Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+from typing import Optional, Dict, Any
+from pydantic import BaseModel, Field, ConfigDict
+from uuid import UUID
+
+from .base import DateTimeModelMixin
+
+
+# Core model config schema (stored in config JSONB field)
+class LLMModelConfigData(BaseModel):
+    """
+    LLM model configuration data.
+    All fields are stored in the config JSONB column.
+    """
+
+    name: str = Field(..., min_length=1, max_length=100, description="Configuration name")
+    provider: str = Field(..., description="LLM provider (e.g., 'openai', 'anthropic', 'ollama')")
+    base_url: str = Field(..., description="API base URL")
+    model: str = Field(..., description="Model name")
+    temperature: float = Field(default=0.7, ge=0.0, le=2.0, description="Temperature parameter")
+    api_key: Optional[str] = Field(None, description="API key (will be encrypted)")
+    max_tokens: Optional[int] = Field(None, gt=0, description="Max tokens for generation")
+
+    # Allow extra fields for extensibility
+    model_config = ConfigDict(extra="allow")
+
+
+# Request schemas
+class LLMModelConfigCreate(LLMModelConfigData):
+    """Request to create a new LLM model configuration."""
+
+    is_default: Optional[bool] = Field(False, description="Set as default configuration")
+
+
+class LLMModelConfigUpdate(BaseModel):
+    """Request to update an existing LLM model configuration."""
+
+    name: Optional[str] = Field(None, min_length=1, max_length=100)
+    provider: Optional[str] = None
+    base_url: Optional[str] = None
+    model: Optional[str] = None
+    temperature: Optional[float] = Field(None, ge=0.0, le=2.0)
+    api_key: Optional[str] = None
+    max_tokens: Optional[int] = Field(None, gt=0)
+    is_default: Optional[bool] = None
+
+    # Allow extra fields for extensibility
+    model_config = ConfigDict(extra="allow")
+
+
+# Response schemas
+class LLMModelConfigResponse(DateTimeModelMixin):
+    """LLM model configuration response."""
+
+    config_id: UUID
+    config: LLMModelConfigData
+    user_id: Optional[UUID] = None
+    group_id: Optional[UUID] = None
+    is_default: bool
+
+    model_config = ConfigDict(from_attributes=True)
+
+
+class LLMModelConfigListResponse(BaseModel):
+    """Response containing list of LLM model configurations."""
+
+    configs: list[LLMModelConfigData]
+    default_config_id: Optional[UUID] = None
+    total: int
+
+
+# Inheritance response (user configs + inherited group configs)
+class LLMModelConfigWithSource(LLMModelConfigData):
+    """Model configuration with source information."""
+
+    config_id: UUID
+    source: str = Field(..., description="Source: 'user' or 'group'")
+    group_name: Optional[str] = Field(None, description="Group name if source is 'group'")
+    is_default: bool
+
+
+class LLMModelConfigInheritedResponse(BaseModel):
+    """Response containing user's effective configs (own + inherited from groups)."""
+
+    configs: list[LLMModelConfigWithSource]
+    default_config: Optional[LLMModelConfigWithSource] = None
+    total: int