Fix TypeError when optional params omitted from array (fixes #736)

[pataar]

Closes #736

Summary

When passing route parameters as an array, omitting optional parameters caused a TypeScript error — even though the parameters were optional. This PR fixes that by making optional parameters truly optional in the generated tuple type.

Before

Given a route like:

interface RouteList {
    'posts.comments.show': [
        { name: 'post'; required: true },
        { name: 'comment'; required: false },
    ];
}

These perfectly valid calls would all cause type errors:

route('posts.comments.show', [2]);        // ❌ Source has 1 element(s) but target requires 2
route('posts.comments.show', ['foo']);     // ❌
route('posts.comments.show', [{ id: 2 }]); // ❌

The workaround was to always pass all parameters or use object syntax instead.

After

All of the above now work as expected — no type errors, no workarounds needed:

route('posts.comments.show', [2]);          // ✅
route('posts.comments.show', ['foo']);       // ✅
route('posts.comments.show', [{ id: 2 }]);  // ✅
route('posts.comments.show', [2, 3]);       // ✅ (still works too)

How it works

The old KnownRouteParamsArray type mapped all parameters to required tuple positions regardless of whether they were optional. The fix splits it into two recursive helper types:

• RequiredParamsTuple — collects required params as required tuple elements
• OptionalParamsTuple — collects optional params as optional tuple elements (?), with ...unknown[] at the end for extra items

So for the route above, the generated type goes from [ParameterValue, ParameterValue, ...unknown[]] to [ParameterValue, ParameterValue?, ...unknown[]].

Test plan

• Uncommented 4 existing TODO test cases that were previously blocked by this bug
• Added new tests for routes where all parameters are optional (route('optional', []) and route('optional', ['foo']))
• All JS and type tests pass

[bakerkretzmar]

Wow........ this is awesome. Thank you so much!