Pass terminalWidth in custom command stdin JSON #308

Summary

Custom Command widgets receive context.data as JSON via stdin, but context.terminalWidth is not included. This makes it impossible for scripts to adapt output based on terminal width.

Current behavior

From the source (dist/ccstatusline.js:57125):

const jsonInput = JSON.stringify(context.data);
let output = execSync3(item.commandPath, {
  encoding: "utf8",
  input: jsonInput,
  // ...
});

context.terminalWidth exists but is not part of context.data, so custom commands can't access it. Standard detection methods (tput cols, stty size, $COLUMNS) all return 80 in the piped stdio context.

Proposed change

Include terminalWidth (or terminal_width) in the JSON passed to custom commands:

{
  "workspace": { "current_dir": "/path/..." },
  "model": { "display_name": "..." },
  "terminal_width": 142
}

Use case

Adaptive label display — show full labels ("ReadCache", "CacheCreate") on wide terminals and abbreviated ("RC", "CC") on narrow ones.

Workaround

Currently using full labels and relying on ccstatusline's own truncation ("..."), which is suboptimal on narrow screens.