build(deps): unify MCP SDK on 1.31.0

[github-actions]

Summary

• Upgrade both MCP SDK example dependencies to exact 1.31.0.
• Add a root npm override so agents@0.20.1's exact 1.30.0 peer requirement does not retain a second SDK installation.
• Regenerate the lockfile with npm 11: one hoisted SDK 1.31.0, matching the example manifests.

Standalone replacement for #212, requested in #212 (comment). I cannot push to the existing Dependabot branch. Its lockfile retains SDK 1.30.0 alongside nested 1.31.0 copies. The override intentionally replaces agents' older peer pin; integration tests exercise the upgraded SDK.

Validation (Node 24 / npm 11)

• Clean npm ci
• npm ls @modelcontextprotocol/sdk: only deduplicated 1.31.0
• npm run build --workspaces --if-present
• Typechecks for @example/computer-mcp and @cloudflare/example-think
• MCP integration suite: 3/3 tests pass
• Biome checks on changed manifests and git diff --check

Full repository CI remains to run on this PR. Non-failing SDK sourcemap warnings appeared during tests.

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[changeset-bot]

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Latest commit: a1cf628

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[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no bugs or issues to report.