feat: agent platform initial commit

- FastAPI + HTMX UI: dashboard, agents CRUD, chat, audit, tools
- SQLite schema: agents, conversations, messages, audit, sessions
- Code-agent sync (agents/*.py -> DB on startup)
- MCP client with health check
- Token auth (Bearer + session)
- LiteLLM integration via llm.py
- Docker Compose: agent-platform + mcp-tools services
- Smoke tests pass: /health 200, /api/agents 200, / 401

agent_platform/agents/base.py

@@ -0,0 +1,37 @@
+"""Pydantic-Schema für hardcoded Agents.
+
+Beispiel:
+    # agents/recherche.py
+    from agents.base import BaseAgent, AgentConfig
+
+    class RechercheAgent(BaseAgent):
+        config = AgentConfig(
+            id="recherche",
+            name="Recherche-Assistent",
+            description="Recherchiert Themen und fasst zusammen.",
+            system_prompt="Du bist ein Recherche-Assistent...",
+            allowed_tools=["http_get"],
+        )
+"""
+from abc import ABC
+from typing import List, Optional
+from pydantic import BaseModel, Field
+
+
+class AgentConfig(BaseModel):
+    """Type-safe Definition eines hardcoded Agents."""
+    id: str = Field(..., pattern=r'^[a-z0-9_-]+$', min_length=1, max_length=64)
+    name: str = Field(..., min_length=1)
+    description: str = ""
+    system_prompt: str = Field(..., min_length=1)
+    allowed_tools: List[str] = []
+    enabled: bool = True
+
+    model: Optional[str] = None
+    temperature: float = Field(default=0.7, ge=0.0, le=2.0)
+    max_tokens: int = Field(default=2000, ge=100, le=32000)
+
+
+class BaseAgent(ABC):
+    """Marker-Base für Code-Agents. Setze `config` als Class-Variable."""
+    config: AgentConfig