Reorder Array#reduce overloads for better type inference

[majiayu000]

Summary

This PR reorders the Array#reduce and Array#reduceRight method overloads to fix incorrect type inference when the initial value type differs from the array element type.

Problem

When using reduce with an initialValue whose type U is assignable to the array element type T (e.g., number assignable to {}), TypeScript incorrectly matches the reduce(callbackfn, initialValue: T): T overload instead of the more specific generic reduce<U>(callbackfn, initialValue: U): U overload.

Example (from issue):

let arrayOfObjs: {}[] = [];
let countOfProps = arrayOfObjs.reduce((sum, obj) => sum + Object.keys(obj).length, 0);
// Error: Operator '+' cannot be applied to types '{}' and 'number'

Solution

Move the generic overload reduce<U> before the reduce(initialValue: T) overload:

// Before
reduce(callbackfn: ...) => T): T;
reduce(callbackfn: ..., initialValue: T): T;
reduce<U>(callbackfn: ..., initialValue: U): U;

// After
reduce(callbackfn: ...) => T): T;
reduce<U>(callbackfn: ..., initialValue: U): U;  // moved up
reduce(callbackfn: ..., initialValue: T): T;

Files Changed

• src/lib/es5.d.ts - ReadonlyArray and Array interfaces
• src/lib/esnext.iterator.d.ts - Iterator interface
• Updated test baselines to reflect new overload order

Test plan

• All existing reduce-related tests pass
• Test baselines updated to reflect new overload ordering
• Verified fix with reproduction cases from issue

Fixes #7014

🤖 Generated with Claude Code

[majiayu000]

Closing this PR as the implementation needs further review. The JSDoc comments were not properly moved with their corresponding function overloads. Will resubmit after proper analysis.