Add MCP tool execution middleware

[Aymericr]

Description

Expose a server-level executeTool hook so stateful MCP hosts can wrap every registered tool for session-local ordering or other execution controls. The callback receives the registered tool name and an execute function, while resources, prompts, and protocol notifications remain unaffected.

This is the public-package prerequisite for serializing hosted Pascal tool calls without blocking MCP cancellation or SSE traffic.

Validation

• bun test packages/mcp/src — 357 tests passed, 1,356 assertions.
• bunx biome check packages/mcp/src/server.ts packages/mcp/src/server.test.ts
• git diff --check
• Package TypeScript build has no diagnostics in changed files; the workspace currently reports eight pre-existing implicit-any diagnostics in packages/mcp/src/tools/scene-query.ts.

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Note

Low Risk
Optional, additive server factory API; behavior is unchanged when executeTool is omitted, with scope limited to tool registration wrapping.

Overview
Adds an optional executeTool hook on createPascalMcpServer so hosts can wrap every registered tool handler (e.g. to serialize access to a stateful bridge) without touching resources, prompts, or other MCP traffic.

When provided, installToolExecutor temporarily wraps server.registerTool so each tool callback runs through { name, execute } before the real handler runs. A new integration test drives get_scene over in-memory transport and asserts the wrapper’s before/after ordering.

^{Reviewed by Cursor Bugbot for commit ff953a1. Bugbot is set up for automated code reviews on this repo. Configure here.}

[pascal]

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