Add Ai::build() for runtime provider configuration overrides

[inkarnation]

Multi-tenant Laravel apps that store per-tenant API credentials in a database have no first-party way to use those credentials per request. The only working pattern today mutates global config(), which leaks between requests under Octane/Swoole.

Fixes #105

Usage

Ai::build() mirrors Cache::build() / Storage::build() — pass a full config array, get a fresh provider instance. Nothing cached under a name, no global state mutated.

use Laravel\Ai\Ai;

// Per-tenant provider built from a full config array
$provider = Ai::build([
    'driver' => 'anthropic',
    'key'    => $tenant->key,
]);

(new MyAgent)->prompt($text, provider: $provider);

// Inline at the call site
(new MyAgent)->prompt($text,
    provider: Ai::build([
        'driver'       => 'openai',
        'key'          => $tenant->key,
        'url'          => $tenant->url,
        'organization' => $tenant->org_id,
    ]),
);

// Routed through an Ai::extend()-registered custom driver
(new MyAgent)->prompt($text,
    provider: Ai::build([
        'driver' => 'my-custom-driver',
        'name'   => 'tenant-x',
        'key'    => $tenant->key,
    ]),
);

// Composable with failover lists alongside named providers
(new MyAgent)->prompt($text, provider: [
    Ai::build(['driver' => 'anthropic', 'key' => $tenant->key]),
    'openai',
]);

[pushpak1300]

fix conflicts ?

[inkarnation]

@pushpak1300 sure, done

[taylorotwell]

I wonder if this should work more like: https://laravel.com/docs/13.x/filesystem#on-demand-disks