codetopo-mcp 0.3.4

Patch release for the MCP server only: codetopo-mcp 0.3.4 is on crates.io; the other crates are unchanged (five at 0.3.3, codetopo-acp at 0.4.0). Release binaries for both agent binaries are attached.

Windows build fixed. codetopo-mcp had never compiled on Windows — its stdio stdout seal used Unix-only fd APIs. The seal now has a Win32 implementation (duplicate the stdout handle for the protocol writer; SetStdHandle to NUL before std's lazy first handle fetch), and CI builds both agent binaries on Windows so this cannot regress silently. Found by the release-binaries pipeline — the first Windows build in the project's history.