gtrash: add page

[prasadabhishek]

Checklist

• The page(s) are in the correct platform directories: common, linux, osx, windows, sunos, android, etc.
• The page description(s) have links to documentation or a homepage.
• The page(s) follow the content guidelines.
• The page(s) follow the style guide.
• The PR contains at most 5 new pages.
• The PR is authored by me, or has been human-reviewed if it was created with AI or machine translation software (see AI-Assisted Development Policy).
• The PR title conforms to the recommended templates.
• Version of the command being documented (if known): 0.16.0
• Reference issue: Page request: gtrash #23645
• Closes: Page request: gtrash #23645

Additional details:

Adds page for gtrash (FreeDesktop.org spec-compliant trash manager and TUI tool) as requested in #23645. Validated locally via tldr-lint and markdownlint.

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