fix(adapters): ignore extra fields in MCP tool args schema to allow security_context

[NIK-TIGER-BILL]

Problem

When using MCPServerAdapter, CrewAI injects a security_context parameter into every tool call. However, MCP tools' inputSchema is defined by external servers and cannot include this internal field. The MCP adapter creates Pydantic models with the default extra="forbid" config, causing Pydantic validation to fail:

ValidationError: Extra inputs are not permitted
  security_context: extra forbidden

Fix

Pass ConfigDict(extra="ignore") when creating the args_schema for MCP tools so that CrewAI-injected fields are silently discarded before the tool receives its arguments.

# Before
args_model = create_model_from_schema(mcp_tool.inputSchema)

# After
args_model = create_model_from_schema(
    mcp_tool.inputSchema,
    __config__=ConfigDict(extra="ignore"),
)

This is scoped to the MCP adapter only — other tool types are unaffected.

Fixes #4796

---

Note

Low Risk
Low risk: scoped to MCP adapter schema creation and only relaxes validation for unexpected fields, with minimal behavioral impact on normal tool inputs.

Overview
Fixes MCP tool invocation failures when CrewAI injects internal fields like security_context by creating the MCP args_schema with ConfigDict(extra="ignore"), so unknown fields are dropped instead of raising Pydantic validation errors.

This change is limited to mcp_adapter.py and only affects argument validation for MCP-adapted tools.

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