Reduce internal tty API surface to the only production-used helper

[Copilot]

The golang.org/x/term review found that internal/tty exposed two helpers with no production callers: IsStdoutTerminal and StderrTerminalWidth. This change trims the package to the single stderr TTY check actually used by the logger and aligns tests with that smaller surface.

• API cleanup

  • Remove unused internal/tty helpers:
    • IsStdoutTerminal()
    • StderrTerminalWidth()
  • Keep IsStderrTerminal() as the only exported helper in the package.

• Test realignment

  • Drop tests that existed only to cover the removed helpers.
  • Replace direct golang.org/x/term assertions in internal/tty tests with a package-level behavior test that swaps os.Stderr to a pipe and verifies it is not treated as a terminal.

• Result

  • internal/tty now reflects actual usage in the codebase instead of carrying uncalled wrapper APIs.

// remaining package surface
func IsStderrTerminal() bool {
	return term.IsTerminal(int(os.Stderr.Fd()))
}

[Copilot]

Pull request overview

This PR trims the internal/tty package down to the single exported helper that is actually used in production (IsStderrTerminal), removing unused wrapper APIs and updating the unit tests to validate behavior via a pipe-backed os.Stderr.

Changes:

• Removed unused exported helpers from internal/tty: IsStdoutTerminal() and StderrTerminalWidth().
• Simplified internal/tty package documentation to match the reduced surface.
• Updated internal/tty tests to validate IsStderrTerminal() behavior by swapping os.Stderr to a pipe, and dropped tests that only existed for the removed helpers.

Show a summary per file

File	Description
internal/tty/tty.go	Removes unused exported helpers, leaving only IsStderrTerminal() as the package API.
internal/tty/tty_test.go	Removes tests tied to deleted helpers and adds a pipe-backed stderr behavior test for IsStderrTerminal().

Copilot's findings

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• Files reviewed: 2/2 changed files
• Comments generated: 0