feat(ui): add composer enter-to-send toggle (#3178)

* feat(ui): add composer enter-to-send toggle and native hardware-keyboard detection

Replaces the settings-page "Enter sends with a keyboard attached" checkbox with
an EnterKeyToggle in the composer footer: plain Enter submits / Shift+Enter
inserts a newline when enabled, Shift+Enter submits / Enter inserts a newline
when disabled. Ctrl/Cmd+Enter always submits as the soft-keyboard fallback.
Persisted as enterToSend.

Adds the Android HardwareKeyboardPlugin: scans input devices for an alphabetic
physical keyboard (ignoring phantom key/sensor devices), re-answers on config
changes/foreground, and confirms attachment from real hardware key events.
MainActivity surfaces key events to it before the WebView consumes them. The
composer and draft layout start keyboard-aware instead of inferring one focus
late; ComposerEditor preserves Enter modifiers through CodeMirror's deferred
re-dispatch so the toggle can tell Shift/Ctrl+Enter from plain Enter.

Removes the settings search entry and i18n keys for the old checkbox.

* refactor(ui): keep enter-to-send branch focused

* fix(ui): preserve enter-toggle taps on touch

* fix(ui): preserve enter key defaults and move setting

* fix(ui): keep enter setting lint-clean

* fix(i18n): preserve current Turkish message parity

* fix(settings): persist enter-to-send preference

* fix(ui): clarify enter-to-send setting

* fix(ui): apply enter preference on desktop

* fix(ui): match enter setting focus mode default

* test(ui): cover enter key policy matrix

* fix(ui): harden deferred enter handling

* fix(chat): preserve untouched Enter policy and validate settings

---------

Co-authored-by: Bohdan Triapitsyn <artmore@protonmail.com>

packages/ui/src/lib/persistence.test.ts

@@ -261,6 +261,16 @@ describe('updateDesktopSettings', () => {
     }
   });
 
+  test('applies enterToSendConfigured when it arrives without enterToSend', async () => {
+    useUIStore.setState({ enterToSend: false, enterToSendConfigured: false });
+    registerSettingsSave(async () => ({ enterToSendConfigured: true }));
+
+    await updateDesktopSettings({ enterToSendConfigured: true });
+
+    expect(useUIStore.getState().enterToSend).toBe(false);
+    expect(useUIStore.getState().enterToSendConfigured).toBe(true);
+  });
+
   test('reports an error without applying a malformed fallback settings response', async () => {
     const previousFetch = globalThis.fetch;
     const fallbackFetch: typeof fetch = async () => new Response(JSON.stringify('ok'), {