feat: clean up own data on deactivation and uninstall

Deactivation now clears the endpoint-check transient and the cached rewrite
rules (forcing WordPress to regenerate them without this plugin's routes on
the next request) and activation asks mcp-oauth to re-flush its own rules.
uninstall.php removes all own options/transient/cron/table across every site
of a network, delegating to the new self-contained LIT\MCP\Uninstaller class
so it works without the plugin's autoloader and is unit-testable on its own.
mcp-oauth's data (JWT secret, rewrite marker, refresh-token meta, application
passwords) is left untouched, as is every post/attachment/revision.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01At3V6SjwbMe6eMzVGW3Hs7

tests/Unit/LifecycleTest.php

@@ -16,20 +16,23 @@ final class LifecycleTest extends TestCase
         parent::tearDown();
     }
 
-    public function testActivateInstallsTheTableAndSchedulesTheCleanup(): void
+    public function testActivateInstallsTableSchedulesCleanupAndRequestsOauthRewriteFlush(): void
     {
         $GLOBALS['wpdb'] = Mockery::mock(\wpdb::class)->makePartial();
         Functions\expect('dbDelta')->once();
         Functions\expect('update_option')->once()->with('lit_mcp_db_version', '1');
         Functions\when('wp_next_scheduled')->justReturn(false);
         Functions\expect('wp_schedule_event')->once();
+        Functions\expect('delete_option')->once()->with('wpmedia_mcp_oauth_rewrite_version');
 
         Lifecycle::activate();
     }
 
-    public function testDeactivateUnschedulesTheCleanup(): void
+    public function testDeactivateRemovesCronTransientAndStoredRewriteRules(): void
     {
         Functions\expect('wp_clear_scheduled_hook')->once()->with('lit_mcp_log_cleanup');
+        Functions\expect('delete_transient')->once()->with('lit_mcp_endpoint_check');
+        Functions\expect('delete_option')->once()->with('rewrite_rules');
 
         Lifecycle::deactivate();
     }