chore: bump dependencies to pick up security fixes (#52)

### what

- Run `uv lock --upgrade` to upgrade dependencies 
- Advance version string to 2026.04.0

### why

To pull in security fixes - fastmcp 3.2.0 carries 3 CVE fixes, 
including one critical.

### testing

Existing test suite passes (`just test`). No API surface was changed;
this is a pure dependency update.

### docs

No docs needed.

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Version 2026.02.0

Version 0.1.1

Version 0.1.0