EZC: "Did you mean?" suggestions for typos

[SchoolyB]

Typo Suggestions

When the compiler encounters an undefined identifier, suggest the closest match from the current scope.

error[E3001]: undefined variable 'countr'
  --> main.ez:15:5
   |
15 |     countr++
   |     ^^^^^^
   |
   = help: did you mean 'counter'?

Checklist

• Implement Levenshtein distance (or similar edit distance) function
• On undefined variable/function/type, search scope for names within edit distance ≤ 2
• Suggest the closest match in the help text
• Apply to: variable names, function names, struct/enum type names, module names, enum member names
• Suggest EZ keywords when identifier is close to a keyword (e.g. `retrun` → `return`)

Dependencies

• Requires type checker / symbol table to know what's in scope