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

src/Lifecycle.php

@@ -4,12 +4,15 @@ declare(strict_types=1);
 
 namespace LIT\MCP;
 
+use LIT\MCP\Admin\ConnectionStatus;
 use LIT\MCP\ChangeLog\ChangeLog;
 use LIT\MCP\ChangeLog\ChangeLogCleanup;
 use LIT\MCP\ChangeLog\ChangeLogInstaller;
+use WPMedia\MCP\OAuth\Bootstrap as OAuthBootstrap;
 
 /**
- * Activation and deactivation hooks (registered in wp-lit-mcp.php).
+ * Activation and deactivation hooks (registered in wp-lit-mcp.php). Uninstall
+ * lives in uninstall.php.
  */
 final class Lifecycle
 {
@@ -18,10 +21,20 @@ final class Lifecycle
         $log = new ChangeLog();
         (new ChangeLogInstaller($log))->install();
         (new ChangeLogCleanup($log, new Limits()))->ensureScheduled();
+
+        if (class_exists(OAuthBootstrap::class)) {
+            // mcp-oauth's public API: rewrite its /oauth and /.well-known rules on the next init.
+            OAuthBootstrap::schedule_rewrite_flush();
+        }
     }
 
     public static function deactivate(): void
     {
         wp_clear_scheduled_hook(ChangeLogCleanup::HOOK);
+        delete_transient(ConnectionStatus::ENDPOINT_TRANSIENT);
+        // WordPress regenerates the rules on the next request – without those of this now
+        // inactive plugin. Calling flush_rewrite_rules() here instead would rewrite them
+        // including our rules, because the plugin is still loaded during this request.
+        delete_option('rewrite_rules');
     }
 }