Support custom Plausible script path

Add a PLAUSIBLE_SCRIPT config option so site-specific scripts
(js/pa-XXXXX.js) and legacy script extensions can be proxied. The
script is still served locally from /js/script.js and the cache key
is derived from the script URL so changing the script takes effect
immediately.

Closes #14

tests/PlausibleProxyTest.php

@@ -1,35 +1,65 @@
 <?php
 
-use Illuminate\Support\Facades\Cache;
 use Illuminate\Support\Facades\Http;
 
-it('returns plausible script from cache', function () {
-    Cache::put('plausible_script_js', 'console.log("Cached script");', now()->addHours(6));
-
-    $response = $this->get('/js/script.js');
-
-    $response->assertStatus(200)
-        ->assertHeader('Content-Type', 'application/javascript')
-        ->assertSee('Cached script');
-});
-
-it('fetches plausible script if not cached', function () {
+it('fetches plausible script and caches it', function () {
     Http::fake([
-        config('plausible-proxy.domain').'/js/script.js' => Http::response('console.log("Plausible script");', 200),
+        'https://plausible.io/js/script.js' => Http::response('console.log("Plausible script");', 200),
     ]);
 
-    $response = $this->get('/js/script.js');
-
-    $response->assertStatus(200)
+    $this->get('/js/script.js')
+        ->assertStatus(200)
         ->assertHeader('Content-Type', 'application/javascript')
         ->assertSee('Plausible script');
 
-    expect(Cache::get('plausible_script_js'))->toBe('console.log("Plausible script");');
+    $this->get('/js/script.js')
+        ->assertStatus(200)
+        ->assertSee('Plausible script');
+
+    Http::assertSentCount(1);
+});
+
+it('fetches a custom script path', function () {
+    config()->set('plausible-proxy.script', 'js/pa-12345ABCDE.js');
+
+    Http::fake([
+        'https://plausible.io/js/pa-12345ABCDE.js' => Http::response('console.log("Custom script");', 200),
+    ]);
+
+    $this->get('/js/script.js')
+        ->assertStatus(200)
+        ->assertSee('Custom script');
+
+    Http::assertSent(fn ($request) => $request->url() === 'https://plausible.io/js/pa-12345ABCDE.js');
+});
+
+it('handles trailing and leading slashes in domain and script path', function () {
+    config()->set('plausible-proxy.domain', 'https://plausible.example.com/');
+    config()->set('plausible-proxy.script', '/js/script.outbound-links.js');
+
+    Http::fake([
+        'https://plausible.example.com/js/script.outbound-links.js' => Http::response('console.log("Outbound");', 200),
+    ]);
+
+    $this->get('/js/script.js')->assertStatus(200)->assertSee('Outbound');
+});
+
+it('does not serve a cached script after the script path changes', function () {
+    Http::fake([
+        'https://plausible.io/js/script.js' => Http::response('console.log("Old script");', 200),
+        'https://plausible.io/js/pa-12345ABCDE.js' => Http::response('console.log("New script");', 200),
+    ]);
+
+    $this->get('/js/script.js')->assertSee('Old script');
+
+    config()->set('plausible-proxy.script', 'js/pa-12345ABCDE.js');
+
+    $this->get('/js/script.js')->assertSee('New script');
 });
 
 it('handles failed script fetch', function () {
     Http::fake([
-        config('plausible-proxy.domain').'/js/script.js' => Http::response('', 500),
+        'https://plausible.io/js/script.js' => Http::response('', 500),
     ]);
 
     $response = $this->get('/js/script.js');