Release v0.0.74

[attson]

Summary

• release MCP tab groups when sessions close, expire, disconnect, or the server shuts down
• preserve coordinator pool lifecycle callbacks so disconnect cleanup runs reliably
• add a safe manual cleanup for tracked and orphaned MCP groups without closing tabs
• bump root and MCP fallback versions to 0.0.74

Verification

• pnpm test (1,296 tests)
• coordinator, MCP, and extension typechecks
• pnpm build
• git diff --check