fix(cli): filter opencode processes by --port argument

[epheien]

Summary

• Fixed the process filtering logic in lua/opencode/cli/server.lua
• Now correctly filters opencode processes by checking for the --port argument
• This prevents false positives when multiple processes contain "opencode" in their command line

Changes

• Updated the pgrep command to include -lfa flags and filter by --port argument
• Changed PID extraction to properly parse the new pgrep -l output format

This fix ensures that only actual opencode server processes (those started with --port argument) are discovered, improving reliability when multiple processes with similar names are running.

[epheien]

The motivation for this modification is that under macOS, there are many opencode processes, which causes this plugin to be very slow when acquiring ports.

[nickjvandyke]

Thanks for this! I guess the way I use opencode doesn't result in nearly as many processes (last I checked), but this seems great for some users! 😀