feat: port --since filter, -S/--blocks flag, icons terminal isolation, and newest sort aliases (eza#1687, #1667, #1849, #1853)

[fxrdhan]

Description

This PR ports and hardens four high-priority upstream features and bugfixes from eza-community/eza into lsr. Each item is committed as its own granular, atomic commit:

1. Commit 1 (452680ff): feat(filter): implement --since time-based file filtering flag (ported from eza-community/eza#1687)

   • Implements the --since <DURATION> CLI flag to filter and display only files created or modified within the specified duration window (e.g. 10m, 1h, 2d, 1w).
   • Uses humantime for robust human-friendly duration parsing and checks both modified and created timestamps against current time cutoff.
   • Updates documentation (README.md, man/eza.1.md, man/lsr.1.md) and shell completions (bash, zsh, fish, nushell, powershell).
   • Includes dedicated unit and integration tests in src/options/filter.rs, tests/since_flag_tests.rs, and tests/adversarial_since_m1_challenger_tests.rs.

2. Commit 2 (5d1b6c12): feat(view): add -S / --blocks flag for filesystem block counts (ported from eza-community/eza#1667)

   • Adds the -S / --blocks CLI flag (as an alias to --blocksize) to toggle displaying 512-byte allocated filesystem block counts in long table view (-l).
   • Ensures strict mode compliance when -S / --blocks is passed without --long and full parity across short and long flag invocations.
   • Updates documentation, manual pages, and shell completions.
   • Includes dedicated integration tests in tests/blocks_flag_tests.rs, tests/adversarial_blocks_m2_challenger_tests.rs, and tests/adversarial_blocks_m2_challenger2_full_tests.rs.

3. Commit 3 (0d918599): fix(view): decouple icons=auto terminal detection from COLUMNS (ported from eza-community/eza#1849 and eza-community/eza#1843)

   • Decouples --icons=auto terminal detection from terminal-width deduction, querying vars.stdout_is_terminal() directly.
   • Prevents the presence of the COLUMNS environment variable from erroneously enabling Nerd Font icons in non-interactive pipes or file redirects.
   • Includes unit tests in src/options/view.rs and integration tests in tests/icons_auto_terminal_tests.rs.

4. Commit 4 (eb438909): fix(sort): align sort aliases so newest/new sorts newest-first (ported from eza-community/eza#1853)

   • Aligns sort aliases so that --sort=newest and --sort=new map to SortField::ModifiedAge (sorting newest files at the top, matching --sort=age), while old and oldest map to SortField::ModifiedDate (sorting oldest files at the top).
   • Updates documentation (README.md, man/eza.1.md, man/lsr.1.md) and shell completions (bash, zsh, fish, pwsh).
   • Includes unit tests in src/options/filter.rs and dedicated integration tests in tests/sort_aliases_tests.rs.

How Has This Been Tested?

• Test Suite: cargo test --all-targets (all unit and integration tests passing across all test suites, including tests/since_flag_tests.rs, tests/adversarial_since_m1_challenger_tests.rs, tests/blocks_flag_tests.rs, tests/icons_auto_terminal_tests.rs, and tests/sort_aliases_tests.rs).
• Linter: cargo clippy --all-targets --all-features -- -D warnings (0 warnings).
• Formatting: cargo fmt --all -- --check (clean).
• Compliance: reuse lint (100% compliant with REUSE v3.3 specification across 561 files).