Add IRB fix command to rerun with corrected spelling (fixes #179)

[krsinghshubham]

Summary

Implements the feature requested in #179: when using IRB, after a typo triggers a "Did you mean?" error, users can type fix to rerun the previous command with the suggested correction applied. This is similar to thefuck.

Example

irb(main):001> 1.zeor?
# => NoMethodError (undefined method `zeor?' for 1:Integer)
#    Did you mean?  zero?

irb(main):002> fix
# Rerunning with: 1.zero?
# => true

Implementation Details

Architecture

• lib/did_you_mean/irb.rb – Core module with LastError, FixCommand, and MAX_EDIT_DISTANCE = 2
• lib/did_you_mean/irb/eval_patch.rb – Patches IRB::Irb#eval_input to capture correctable exceptions
• lib/did_you_mean/irb/command.rb – Registers the fix command with IRB

Supported Error Types

NoMethodError, NameError, KeyError, NoMatchingPatternKeyError, LoadError

Correction Logic

• Single suggestion only (edit distance ≤ 2)
• Replacement patterns: identifiers, symbols, strings
• Clear user feedback when fix cannot be applied
• Discoverability hint: "Type fix to rerun with the correction." when fix is available
• dym alias for users who use fix as a variable

Changes

• lib/did_you_mean/irb.rb, eval_patch.rb, command.rb
• lib/did_you_mean.rb – auto-requires IRB extension
• README.md – documentation

Fixes #179

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