Add -t flag for sorting by time

[Copilot]

This PR adds a -t flag to sort files by modification time with newest files first, providing better compatibility with GNU coreutils ls -t command.

Currently, users need to use --sort time to achieve time-based sorting. This change adds the more familiar and concise -t flag that behaves identically to the existing --sort time functionality.

Changes Made

• Added -t flag definition in /internal/cli/sort.go that calls sorter.ByTimeAscend(timeType[0]) to sort by modification time (newest first)
• Updated help text in /internal/cli/g.go to include the new flag in the SORTING section
• The implementation reuses existing sorting infrastructure and follows the same pattern as other single-character sorting flags (-S, -X, -U)

Usage Examples

# Before: verbose flag required
g --sort time

# After: concise flag available
g -t

# Both produce identical output (newest files first)
g -t -l
g --sort time -l

The -t flag works with all existing options and formats, maintaining full compatibility with the current functionality while providing the familiar interface that users expect from standard ls command.

Fixes #259.

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[Copilot]

Pull Request Overview

This PR adds a -t flag for time-based sorting to improve compatibility with GNU coreutils ls -t command. The flag provides a concise alternative to the existing --sort time option.

• Adds -t flag that sorts files by modification time with newest files first
• Updates help documentation to include the new flag in the SORTING section
• Maintains full compatibility with existing functionality while providing familiar interface

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
internal/cli/sort.go	Adds new -t BoolFlag with time sorting action
internal/cli/g.go	Updates help text to document the new -t flag