Add 'nudge check' command for CI/linter usage

[jssblck]

Summary

Adds a new nudge check command that validates project files against configured rules, designed for CI pipelines and local linting.

• Exits 0 on success, 1 when issues found
• Supports optional path arguments for targeted checking
• Respects .gitignore and ignores hidden files/directories
• Reports rule violations with file paths, line numbers, and messages

Usage

# Check entire project
nudge check

# Check specific paths
nudge check src/
nudge check "**/*.rs"

# Use in CI (fails build on violations)
nudge check || exit 1

Dogfooding: Before & After

We ran nudge check on this repository to validate it works. Here's what we found and fixed:

Before (42 violations found)

$ cargo run -p nudge -- check
✗ Found 42 issues in 17 files

./packages/nudge/src/rules/schema.rs:1260 [no-unwrap]
  Use `.expect("descriptive error message")` instead of `.unwrap()`, then retry.

./packages/nudge/src/rules/schema.rs:1276 [no-unwrap]
  Use `.expect("descriptive error message")` instead of `.unwrap()`, then retry.

./packages/nudge/tests/it/bash.rs:77 [no-unwrap]
  Use `.expect("descriptive error message")` instead of `.unwrap()`, then retry.

./packages/nudge/tests/it/bash.rs:153 [no-unwrap]
  Use `.expect("descriptive error message")` instead of `.unwrap()`, then retry.

... (36 more violations across schema.rs, rules.rs, snippet.rs, and test files)

Checked 60 files against 6 rules

After (0 violations)

$ cargo run -p nudge -- check
✓ Checked 60 files against 6 rules
  - .nudge.yaml: 6 rules

Changes

1. New nudge check command (src/cmd/check.rs)

   • Walks project files respecting .gitignore
   • Evaluates rules against file contents
   • Reports violations with source locations
   • Supports glob patterns for targeted checking

2. Updated rules to use tree-sitter (.nudge.yaml)

   • prefer-pretty-assertions: Avoids false positive on pretty_assert_eq!
   • no-lhs-type-annotations: Avoids false positive on pattern matching
   • no-inline-imports: Ignores use in mod tests blocks
   • no-unwrap: Matches method calls only, not doc comments/strings

3. Fixed all violations in source and test files

   • Replaced .unwrap() with .expect() (36 occurrences)
   • Used turbofish syntax instead of LHS type annotations

Testing

• All 96 tests pass
• nudge check reports zero violations on this repository