Add comprehensive ripgrep compatibility tests

[Shengyu Fu (shengyfu)]

Summary

Adds 58 new integration tests to \ grep-cli/tests/ripgrep_compat.rs\ (from 41 → 99 tests), covering ripgrep-compatible CLI flags that were previously untested or weakly tested.

New test coverage

Category	Tests
Case-insensitive (-i)	2
Smart case (-S)	3
Fixed strings (-F)	3
Word boundary (-w)	2
Invert match (-v)	2
Only matching (-o)	2
Max count (-m)	2
Count (-c)	2
Files with matches (-l)	2
Multiple patterns (-e)	2
Pattern file (-f)	1
Context lines (-A/-B/-C)	5
JSON output (--json)	4
Vimgrep output (--vimgrep)	2
Trim (--trim)	1
Null separator (-0)	2
Heading (--no-heading)	1
Color (--color never)	1
Hidden (--hidden)	1
No-ignore (--no-ignore)	1
Unrestricted (-u/-uu)	2
Glob negation (!pattern)	1
Combined flag interactions	8
Exit codes & edge cases	7

All 199 workspace tests pass, clippy is clean.

[Copilot]

Pull request overview

Adds a large set of new integration tests to improve tgrep CLI compatibility coverage with ripgrep-style flags, primarily exercising behavior under --no-index (brute-force) execution.

Changes:

• Expands tgrep-cli/tests/ripgrep_compat.rs with many new tests covering common ripgrep flags (case handling, fixed strings, word boundary, invert match, context, JSON, vimgrep, trim, null separators, ignore/hidden, and combinations).
• Adds additional edge-case and exit-code assertions.

Show a summary per file

File	Description
tgrep-cli/tests/ripgrep_compat.rs	Adds extensive ripgrep-compatibility integration tests across many CLI flags and flag interactions.

Copilot's findings

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Comments suppressed due to low confidence (1)

tgrep-cli/tests/ripgrep_compat.rs:1968

• Same as above: the git init precondition is ignored here. If initialization fails, -u may behave differently (since there’s no repo/.gitignore), making this test environment-dependent. Please assert git init succeeded (or skip when git is unavailable).

        .assert()
        .success()
        .stdout(predicate::str::contains("unrestricted secret"));
}

• Files reviewed: 1/1 changed files
• Comments generated: 2