[Proposal] Add Multi-Gateway Tool Deduplication Sample in 01-features

### Problem
Whenever a developer wants to connect a single AgentCore Runtime to **more than one** AgentCore Gateway, they will encounter a tool identifier collision.

By design, AgentCore Gateways automatically inject built-in infrastructure tools (such as the `x_amz_bedrock_agentcore_search` semantic search tool). If a developer merges tools from multiple gateways and passes them directly to the `Agent` constructor, the framework crashes with a `ValueError: Tool name already exists`.

While a prominent use case for this is building advanced multi-agent architectures (e.g., separating a "DomainSpecific" gateway from a "SharedUtility" gateway to achieve high cohesion), this issue fundamentally affects *any* implementation attempting to consume multiple gateways simultaneously.

### Proposed Solution
I have already implemented a solution for this, and I will be submitting a Pull Request shortly to contribute it to the repository.

My PR will add a new sample under `01-features/07-centralize-and-govern-your-ai-infrastructure/01-gateway/04-advanced-concepts/multi-gateway-tool-deduplication/`.
The sample contains:
- A comprehensive `README.md` explaining the problem, the architectural context, and the exact error.
- A standalone `deduplicate.py` script demonstrating how to cleanly deduplicate tools by name before Agent initialization, preserving the original object and deeply logging the discarded duplicates.

Start with the proposed path under 01-features/07-centralize-and-govern-your-ai-infrastructure/01-gateway/04-advanced-concepts/multi-gateway-tool-deduplication/. Review the requested README.md and deduplicate.py sample, then confirm that the documentation explains the tool-name collision and the script demonstrates deduplication before Agent initialization.

Written by the indexing model from the issue text.