[changelog] Add changelog for v1.0.7

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Protected files: CHANGELOG.md

Adds the changelog entry for the v1.0.7 stable release.

Changes documented (4 highlighted features, 6 other changes):

• In-process (FFI) transport for Node.js, Rust, Python, and Go
• Tool search configuration support
• Opaque metadata passthrough on tool definitions
• canvasProvider session field, enableManagedSettings, request handler agent metadata propagation
• Rust serialization determinism and native-tls improvements
• .NET Windows in-process teardown bugfix
• 4 new contributors

Generated by Release Changelog Generator · sonnet46 1.2M · ◷

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Protected files were modified in this pull request and require manual scrutiny before merge.

Please verify that each protected-file change is intentional, policy-compliant, and safe:

• Protected files: CHANGELOG.md