test(core): cover UpdateChannels and the module extension registries

First batch of the src/Core coverage effort — pure in-memory / settings-driven
classes that had zero tests:

- UpdateChannelsTest: per-repo channel resolution (main/bin/fanout read their
  own update_channel_* setting), the 'unstable'->'beta' legacy alias, the
  unknown/empty -> 'stable' fallback, and forRepo() dispatch (BIN/FANOUT map to
  their channel; MAIN/UPDATE/PROXY/unknown follow MAIN). Seeded via
  SettingsManager::set().

- ModuleRegistriesTest: TableRegistry (register/lookup/last-wins), TopbarRegistry
  (order sort, per-label last-wins, export-page + log-type flags), QuickToolsRegistry
  (group rows, keys, handler lookup) and PermissionRegistry (ordered deduped set).

+15 tests, 41 assertions. Suite: 595 tests, 0 errors.

tests/Unit/ModuleRegistriesTest.php

@@ -0,0 +1,131 @@
+<?php
+
+use XcVm\Core\Module\PermissionRegistry;
+use XcVm\Core\Module\QuickToolsRegistry;
+use XcVm\Core\Module\TableRegistry;
+use XcVm\Core\Module\TopbarRegistry;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Module extension registries — the in-memory surfaces modules register into
+ * during boot (serverSide tables, topbar buttons, quick-tools actions, reseller
+ * sub-permissions). They hold process-global static state, so each test resets
+ * them; these lock down the register/lookup/override/order contracts the core
+ * controllers and views depend on.
+ */
+final class ModuleRegistriesTest extends TestCase {
+
+	protected function setUp(): void {
+		TableRegistry::reset();
+		TopbarRegistry::reset();
+		QuickToolsRegistry::reset();
+		PermissionRegistry::reset();
+	}
+
+	protected function tearDown(): void {
+		TableRegistry::reset();
+		TopbarRegistry::reset();
+		QuickToolsRegistry::reset();
+		PermissionRegistry::reset();
+	}
+
+	// ── TableRegistry ────────────────────────────────────────────────
+
+	public function testTableRegistryRegistersAndLooksUpAHandler(): void {
+		$this->assertFalse(TableRegistry::has('watch_output'));
+		$this->assertNull(TableRegistry::get('watch_output'));
+
+		$handler = static fn(array $r, int $s, int $l, bool $api): array => $r;
+		TableRegistry::register('watch_output', $handler);
+
+		$this->assertTrue(TableRegistry::has('watch_output'));
+		$this->assertSame($handler, TableRegistry::get('watch_output'));
+	}
+
+	public function testTableRegistryIsLastWinsPerId(): void {
+		$first = static fn(): array => ['first'];
+		$second = static fn(): array => ['second'];
+		TableRegistry::register('dup', $first);
+		TableRegistry::register('dup', $second);
+
+		$this->assertSame($second, TableRegistry::get('dup'));
+	}
+
+	public function testTableRegistryResetClearsHandlers(): void {
+		TableRegistry::register('x', static fn(): array => []);
+		TableRegistry::reset();
+		$this->assertFalse(TableRegistry::has('x'));
+	}
+
+	// ── TopbarRegistry ───────────────────────────────────────────────
+
+	public function testTopbarEntriesAreReturnedOrderedByOrder(): void {
+		TopbarRegistry::add('watch', 'Later', '/z', null, null, 200);
+		TopbarRegistry::add('watch', 'Sooner', '/a', 'adv', 'id="s"', 50);
+
+		$page = TopbarRegistry::forPage('watch');
+
+		$this->assertSame(['Sooner', 'Later'], array_keys($page), 'ascending by order');
+		$this->assertSame(['/a', 'adv', 'id="s"'], $page['Sooner'], 'spec = [url, permission, attr]');
+		$this->assertSame(['/z', null, null], $page['Later']);
+		$this->assertSame(['watch'], TopbarRegistry::pages());
+	}
+
+	public function testTopbarAddIsLastWinsPerLabelOnAPage(): void {
+		TopbarRegistry::add('movies', 'Export', '/old');
+		TopbarRegistry::add('movies', 'Export', '/new', null, null, 10);
+
+		$page = TopbarRegistry::forPage('movies');
+		$this->assertCount(1, $page);
+		$this->assertSame(['/new', null, null], $page['Export']);
+	}
+
+	public function testTopbarForUnknownPageIsEmpty(): void {
+		$this->assertSame([], TopbarRegistry::forPage('nope'));
+		$this->assertSame([], TopbarRegistry::pages());
+	}
+
+	public function testTopbarExportPageAndLogTypeFlags(): void {
+		$this->assertFalse(TopbarRegistry::isExportPage('reports'));
+		$this->assertNull(TopbarRegistry::logType('reports'));
+
+		TopbarRegistry::markExportPage('reports');
+		TopbarRegistry::setLogType('reports', 'plex_logs');
+
+		$this->assertTrue(TopbarRegistry::isExportPage('reports'));
+		$this->assertSame('plex_logs', TopbarRegistry::logType('reports'));
+		$this->assertFalse(TopbarRegistry::isExportPage('other'));
+	}
+
+	// ── QuickToolsRegistry ───────────────────────────────────────────
+
+	public function testQuickToolsGroupsCollectRowsAndHandlers(): void {
+		$clear = static function (): void {};
+		$sync = static function (): void {};
+		QuickToolsRegistry::add('cache', 'clear_cache', 'Clear cache', $clear);
+		QuickToolsRegistry::add('cache', 'sync_cache', 'Sync cache', $sync);
+		QuickToolsRegistry::add('epg', 'reload_epg', 'Reload EPG', static function (): void {});
+
+		$this->assertSame(['cache', 'epg'], QuickToolsRegistry::groups());
+		$this->assertSame(
+			[['clear_cache', 'Clear cache'], ['sync_cache', 'Sync cache']],
+			QuickToolsRegistry::forGroup('cache')
+		);
+		$this->assertSame(['clear_cache', 'sync_cache', 'reload_epg'], QuickToolsRegistry::keys());
+		$this->assertSame($sync, QuickToolsRegistry::handler('sync_cache'));
+		$this->assertNull(QuickToolsRegistry::handler('missing'));
+		$this->assertSame([], QuickToolsRegistry::forGroup('missing'));
+	}
+
+	// ── PermissionRegistry ───────────────────────────────────────────
+
+	public function testPermissionRegistryIsAnOrderedDedupedSet(): void {
+		$this->assertSame([], PermissionRegistry::keys());
+
+		PermissionRegistry::add('plex_manage');
+		PermissionRegistry::add('watch_view');
+		PermissionRegistry::add('plex_manage');
+
+		$this->assertSame(['plex_manage', 'watch_view'], PermissionRegistry::keys(), 'registration order, deduped');
+	}
+}