VersaPadLink never closes itself; get_board_status()/load_from_board()/
write_to_board() were leaving the exclusive COM port open for the rest of
the MCP server process's lifetime after a single call. That locked out
Live-Sync, the official VersaGUI, and even the MCP server's own next call
with "busy", live-observed today after a single write_to_board() call. Each
of the three now closes the link in a finally block regardless of outcome.
Also documented in AGENTS.md: this environment can run several independent
versapad_mcp_server.py processes at once, each with its own in-memory
state, which caused a write_to_board() call to silently write blank data
from a fresh process instead of the config that had just been built up on
another one (ACK still said {"ok": true}). Recommended workaround noted
there: load_local() right before write_to_board(), and read back with
load_from_board() + get_profile() afterwards instead of trusting the ACK.
