fix: force UTF-8 encoding for non-UTF8 locales

[cardmagic]

Summary

• Force UTF-8 encoding in CLI executable to prevent encoding errors in C/POSIX locales
• Bump version to 2.3.1

Problem

When running classifier in environments with non-UTF8 locales (like Homebrew's test sandbox which uses LC_ALL=C), the CLI fails with:

Error: "\xC2" on US-ASCII

Solution

Explicitly set Encoding.default_external and Encoding.default_internal to UTF-8 at CLI startup.

Test

LC_ALL=C classifier -r sms-spam-filter "test message"
# Now works instead of failing with encoding error

[greptile-apps]

Greptile Summary

Fixed encoding errors in non-UTF8 locales (like Homebrew's C/POSIX test sandbox) by forcing UTF-8 encoding in the CLI executable and bumped version to 2.3.1.

• Added Encoding.default_external and Encoding.default_internal settings to exe/classifier
• Bumped version from 2.3.0 to 2.3.1
• One redundant comment should be removed per project guidelines

Confidence Score: 5/5

• This PR is safe to merge with minimal risk
• Simple, focused fix that addresses a real bug in non-UTF8 locales. The encoding fix is the correct Ruby idiom for this problem, and the version bump is appropriate. Only minor style improvement suggested (removing redundant comment).
• No files require special attention

Important Files Changed

Filename	Overview
exe/classifier	added UTF-8 encoding fix for non-UTF8 locales; one redundant comment
lib/classifier/version.rb	version bumped to 2.3.1

Sequence Diagram

sequenceDiagram
    participant User
    participant CLI as exe/classifier
    participant Ruby as Ruby Runtime
    participant ClassifierCLI as Classifier::CLI
    
    User->>CLI: Execute classifier command
    CLI->>Ruby: Set Encoding.default_external = UTF-8
    CLI->>Ruby: Set Encoding.default_internal = UTF-8
    Note over CLI,Ruby: Forces UTF-8 encoding for C/POSIX locales
    CLI->>ClassifierCLI: require 'classifier/cli'
    CLI->>ClassifierCLI: new(ARGV).run
    ClassifierCLI-->>CLI: result hash
    CLI->>CLI: warn result[:error] unless empty?
    CLI->>CLI: puts result[:output] unless empty?
    CLI->>User: exit result[:exit_code]

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[greptile-apps]

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[greptile-apps]

style: comment restates what the code already shows

Suggested change

# Force UTF-8 encoding for proper handling of model data and user input

_{Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!}

Prompt To Fix With AI

This is a comment left during a code review.
Path: exe/classifier
Line: 4:4

Comment:
**style:** comment restates what the code already shows

```suggestion
```

<sub>Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!</sub>

How can I resolve this? If you propose a fix, please make it concise.