JS-619 Fix S3403 false positive for indexed access types

[vibe-bot-ss]

Summary

• Fixed false positive in rule S3403 (different-types-comparison)
• Issue: Rule incorrectly flagged comparisons involving indexed access types from generic Records
• Solution: Added check to allow comparisons with unknown types and indexed access types

Details

The rule was raising false positives when comparing indexed access types (e.g., T[K] where T extends Record<string, unknown>) with string literals. Since these types represent unknown values at compile time, they can legitimately be compared with any type using strict equality operators.

Example of Fixed False Positive:

class Foo<T extends Record<string, unknown>> {
  constructor(private readonly foo: T) {}

  reproduction<Key extends keyof T>(key: Key) {
    return this.foo[key] === 'foo';  // No longer raises FP
  }
}

Test plan

• Unit tests pass
• Rulings pass
• Build passes
• Added test case for the false positive scenario

Fixes JS-619

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