fix: allow aliases with explicit func type annotations

[nickita-khylkouski]

Summary

Fixes #91 - Type error when adding aliases with explicit func type annotations.

Problem

When using buildCommand with an explicit type annotation on the func parameter:

buildCommand({
  func: ({ repo }: { repo: string }) => {},
  parameters: {
    flags: { repo: { kind: 'parsed', parse: String } },
    aliases: { r: 'repo' },  // ❌ Error: 'string' not assignable to 'never'
  }
});

Root Cause

When func has an explicit type annotation, TypeScript's NoInfer wrapper prevents type inference from flowing to parameters. This causes keyof FLAGS to become never, which makes Aliases<never> - a type that only accepts undefined.

Solution

Modified TypedCommandFlagParameters to use Aliases<string> when keyof FLAGS is never:

• When FLAGS can be inferred → strict type checking (Aliases<keyof FLAGS>)
• When FLAGS cannot be inferred → fallback to Aliases<string> with runtime validation

Changes

• packages/core/src/parameter/types.ts - Modified TypedCommandFlagParameters conditional type
• packages/core/tests/type-inference.spec.ts - Added 4 type-level tests (positive, negative, edge case)
• packages/core/tests/alias-runtime.spec.ts - Added 30 runtime tests for alias validation

Trade-off

This is a necessary trade-off due to TypeScript's type inference limitations:

• Compile-time: Invalid alias targets are allowed when keyof FLAGS is never
• Runtime: Invalid alias targets are caught by existing validation in resolveAliases
• Benefit: Aliases now work with explicit function types (a valid and common pattern)

Test Results

• ✅ All 1310 tests pass
• ✅ 100% code coverage maintained
• ✅ 34 new tests added (4 type-level, 30 runtime)