feat(api): integrate MCP tools support in Ollama chat route

Add support for Model Context Protocol (MCP) tools in the Ollama chat API. Detect model capabilities to use native tools or prompt engineering. Handle tool calls, execute them via MCPExecutor, and inject results back into the conversation for seamless tool-assisted responses. This enhances chat functionality by enabling external tool integration.

database/schema.sql

@@ -73,6 +73,20 @@ CREATE TABLE IF NOT EXISTS mcp_cache_metadata (
   updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
 );
 
+-- Tabela para rastrear MCPs ativos por conversa
+CREATE TABLE IF NOT EXISTS active_mcps (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  conversation_id TEXT NOT NULL,
+  mcp_id TEXT NOT NULL,
+  enabled INTEGER DEFAULT 1,
+  created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+  FOREIGN KEY (conversation_id) REFERENCES conversations(id) ON DELETE CASCADE,
+  UNIQUE(conversation_id, mcp_id)
+);
+
+CREATE INDEX IF NOT EXISTS idx_active_mcps_conversation ON active_mcps(conversation_id);
+CREATE INDEX IF NOT EXISTS idx_active_mcps_mcp ON active_mcps(mcp_id);
+
 -- Índices para performance
 CREATE INDEX idx_messages_conversation ON messages(conversation_id, timestamp);
 CREATE INDEX idx_conversations_updated ON conversations(updated_at DESC);