fix: core and trees translations never loaded under any locale

Found while fixing the identical bug shape reported in php-tenant.
Both LangServiceProvider::loadTranslations() and Trees\Boot::boot()
registered their translation hint path as the locale subfolder itself
(__DIR__.'/en_GB' and __DIR__.'/Lang/en_GB') instead of its parent.
loadTranslationsFrom() appends "/{locale}/{group}.php" to whatever
hint it is given, so Laravel was looking for
src/Core/Lang/en_GB/en_GB/core.php and
src/Mod/Trees/Lang/en_GB/en_GB/trees.php — neither ever existed. Every
`core::*` key (framework branding/UI text, per this module's own
CLAUDE.md) and every `trees::*` key round-tripped back out as the raw
key instead of resolving, for every locale, since these files were
added.

LangServiceProvider also had a second, now-redundant call guarded by
is_dir(__DIR__.'/en') meant to register a base-locale fallback; folded
away since a single correct hint already covers every locale Laravel
tries via the fallback chain the same provider sets up in
setupFallbackChain().

Added tests/Feature/CoreTranslationsTest.php and
tests/Feature/TreesTranslationsTest.php, each registering the
respective provider directly (the base TestCase only wires
LifecycleEventProvider) and asserting a known key resolves under
en_GB. Both fail on the pre-fix code with the key echoed back
unresolved.

phpstan level 1 clean, pint clean, full Pest suite 448 failed/567
passed (two more passing than before, zero regressions — the 448 are
the pre-existing dappcore/php-tenant-shaped gap noted in the previous
commit).

Co-Authored-By: Virgil <virgil@lethean.io>

Author: Snider

src/Core/Lang/LangServiceProvider.php

@@ -141,15 +141,20 @@ protected function registerCommands(): void
 
     /**
      * Load translation files from the Lang directory.
+     *
+     * loadTranslationsFrom() registers a *hint path* that Laravel appends
+     * "/{locale}/{group}.php" onto at resolution time — it must NOT already
+     * contain the locale segment. The files live at Lang/en_GB/core.php (and
+     * would live at Lang/en/core.php for the fallback), so the hint is the
+     * Lang directory itself; passing __DIR__.'/en_GB' made Laravel look for
+     * Lang/en_GB/en_GB/core.php, which never existed, so `core::*` keys
+     * never resolved for any locale. One hint covers every locale Laravel
+     * tries via the fallback chain below, so there is nothing further to
+     * register for the 'en' fallback.
      */
     protected function loadTranslations(): void
     {
-        $this->loadTranslationsFrom(__DIR__.'/en_GB', 'core');
-
-        // Also register translations under the base locale (en) for fallback
-        if (is_dir(__DIR__.'/en')) {
-            $this->loadTranslationsFrom(__DIR__.'/en', 'core');
-        }
+        $this->loadTranslationsFrom(__DIR__, 'core');
     }
 
     /**

src/Mod/Trees/Boot.php

@@ -27,7 +27,12 @@ class Boot extends ServiceProvider
 
     public function boot(): void
     {
-        $this->loadTranslationsFrom(__DIR__.'/Lang/en_GB', 'trees');
+        // Hint path must be the Lang directory itself, not the locale
+        // subfolder — Laravel appends "/{locale}/trees.php" at resolution
+        // time. The file lives at Lang/en_GB/trees.php, so passing
+        // Lang/en_GB here made it look for Lang/en_GB/en_GB/trees.php,
+        // which never existed and so never loaded.
+        $this->loadTranslationsFrom(__DIR__.'/Lang', 'trees');
     }
 
     // -------------------------------------------------------------------------

tests/Feature/CoreTranslationsTest.php

@@ -0,0 +1,35 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Core\Tests\Feature;
+
+use Core\Lang\LangServiceProvider;
+use Core\Tests\TestCase;
+use Illuminate\Support\Facades\App;
+
+/**
+ * Regression coverage: LangServiceProvider::loadTranslations() registered
+ * its hint path as __DIR__.'/en_GB', but the file lives at
+ * src/Core/Lang/en_GB/core.php. loadTranslationsFrom() appends
+ * "/{locale}/{group}.php" to whatever hint it is given, so Laravel looked
+ * for src/Core/Lang/en_GB/en_GB/core.php — which never existed — and the
+ * `core::*` namespace never resolved a single key, for any locale, in
+ * production.
+ */
+class CoreTranslationsTest extends TestCase
+{
+    protected function getPackageProviders($app): array
+    {
+        return array_merge(parent::getPackageProviders($app), [
+            LangServiceProvider::class,
+        ]);
+    }
+
+    public function test_core_namespace_translations_load_under_en_gb_locale(): void
+    {
+        App::setLocale('en_GB');
+
+        $this->assertSame('Core PHP', trans('core::core.brand.name'));
+    }
+}

tests/Feature/TreesTranslationsTest.php

@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Core\Tests\Feature;
+
+use Core\Mod\Trees\Boot;
+use Core\Tests\TestCase;
+use Illuminate\Support\Facades\App;
+
+/**
+ * Regression coverage: Core\Mod\Trees\Boot::boot() registered its
+ * translations hint as __DIR__.'/Lang/en_GB', but the file lives at
+ * Lang/en_GB/trees.php. loadTranslationsFrom() appends
+ * "/{locale}/{group}.php" to whatever hint it is given, so Laravel looked
+ * for Lang/en_GB/en_GB/trees.php — which never existed — and the
+ * `trees::*` namespace never resolved a single key, for any locale.
+ */
+class TreesTranslationsTest extends TestCase
+{
+    protected function getPackageProviders($app): array
+    {
+        return array_merge(parent::getPackageProviders($app), [
+            Boot::class,
+        ]);
+    }
+
+    public function test_trees_namespace_translations_load_under_en_gb_locale(): void
+    {
+        App::setLocale('en_GB');
+
+        $this->assertSame('Trees for Agents', trans('trees::trees.hero.badge'));
+    }
+}