htmlviewer-directediting: HTML rendering in Nextcloud iOS app

- htmlviewer: IEditor + Bridge + srcdoc iframe template + content controller
- text app: open() bridges text/html to htmlviewer template
- idempotent install.sh for re-deployment after app updates
- iPhone-tested 2026-09-11

patches/htmlviewer/directEditing-template.php

@@ -0,0 +1,37 @@
+<?php
+/**
+ * SPDX-FileCopyrightText: 2026 HtmlViewer / patch by Hermes Agent
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ *
+ * DirectEditing template: renders the HTML file in a sandboxed iframe
+ * that fills the whole viewport (works in the iOS/Android WebView).
+ * The file content is embedded as srcdoc, so the iframe needs no
+ * session cookie (mobile WebViews do not share the app session).
+ */
+/** @var array $_ */
+?>
+<style>
+    html, body {
+        margin: 0;
+        padding: 0;
+        height: 100%;
+        overflow: hidden;
+        background-color: var(--color-main-background, #ffffff);
+    }
+    #htmlviewer-frame {
+        position: fixed;
+        top: 0;
+        left: 0;
+        width: 100%;
+        height: 100%;
+        border: 0;
+        background: transparent;
+    }
+</style>
+
+<iframe
+    id="htmlviewer-frame"
+    title="<?php echo htmlspecialchars($_['fileName'] ?? 'HTML'); ?>"
+    srcdoc="<?php echo htmlspecialchars($_['fileContent'] ?? '', ENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML401, 'UTF-8', false); ?>"
+    sandbox="allow-same-origin allow-scripts allow-popups allow-popups-to-escape-sandbox allow-modals"
+></iframe>