feat(coding-agent): refactored usage command into show/reset subcommands

- Added `handleUsageResetCommand` support to list and redeem usage reset credits.
- Refactored `/usage` into `show` and `reset` subcommands and removed `/reset-usage`.
- Handled ACP/TUI `/usage` flows so `show` reports usage and `reset` redeems credits.
- Kept selected theme setting values dirty-colored while selected in the UI list.

packages/coding-agent/src/modes/controllers/command-controller.ts

@@ -1546,7 +1546,7 @@ function renderUsageReports(
 		}
 		if (resetAccountLines.length > 0) {
 			lines.push(
-				`  ${uiTheme.fg("accent", "Saved rate-limit resets")} ${uiTheme.fg("dim", "(/reset-usage to spend)")}`,
+				`  ${uiTheme.fg("accent", "Saved rate-limit resets")} ${uiTheme.fg("dim", "(/usage reset to spend)")}`,
 			);
 			for (const line of resetAccountLines) lines.push(uiTheme.fg("dim", line));
 		}