feat: Send email from UI — inline reply composer & SendEmail mutation (#19363)

## Summary

- **Inline email reply**: Replace external email client redirects
(Gmail/Outlook deeplinks) with an in-app email composer. Users can reply
to email threads directly from the email thread widget or via the
command menu.
- **SendEmail GraphQL mutation**: New backend mutation that reuses
`EmailComposerService` for body sanitization, recipient validation, and
SMTP dispatch via the existing outbound messaging infrastructure.
- **Side panel compose page**: Command menu "Reply" action now opens a
side-panel compose email page with pre-filled To, Subject, and
In-Reply-To fields.

### Backend
- `SendEmailResolver` with `SendEmailInput` / `SendEmailOutputDTO`
- `SendEmailModule` wired into `CoreEngineModule`
- Reuses `EmailComposerService` + `MessagingMessageOutboundService`

### Frontend
- `EmailComposer` / `EmailComposerFields` components
- `useSendEmail`, `useReplyContext`, `useEmailComposerState` hooks
- `useOpenComposeEmailInSidePanel` + `SidePanelComposeEmailPage`
- `EmailThreadWidget` inline Reply bar with toggle composer
- `ReplyToEmailThreadCommand` now opens side-panel instead of external
links

### Seeds
- Added `handle` field to message participant seeds for realistic email
addresses
- Seed `connectedAccount` and `messageChannel` in correct batch order

## Test plan

- [ ] Open an email thread on a person/company record → verify
"Reply..." bar appears below the last message
- [ ] Click "Reply..." → composer opens inline with pre-filled To and
Subject
- [ ] Type a message and click Send → email is sent via SMTP, composer
closes
- [ ] Use command menu Reply action → side panel opens with compose
email page
- [ ] Verify Send/Cancel buttons work correctly in side panel
- [ ] Test with Cc/Bcc toggle in composer fields
- [ ] Verify error handling: invalid recipients, missing connected
account


Made with [Cursor](https://cursor.com)

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Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

packages/twenty-front/src/modules/ui/layout/side-panel/states/sidePanelWidgetFooterActionsState.ts

@@ -0,0 +1,9 @@
+import { type SidePanelFooterAction } from '@/ui/layout/side-panel/types/SidePanelFooterAction';
+import { createAtomState } from '@/ui/utilities/state/jotai/utils/createAtomState';
+
+export const sidePanelWidgetFooterActionsState = createAtomState<
+  SidePanelFooterAction[]
+>({
+  key: 'side-panel/widgetFooterActionsState',
+  defaultValue: [],
+});

packages/twenty-front/src/modules/ui/layout/side-panel/types/SidePanelFooterAction.ts

@@ -0,0 +1,12 @@
+import { type IconComponent } from 'twenty-ui/display';
+
+export type SidePanelFooterAction = {
+  key: string;
+  label: string;
+  Icon?: IconComponent;
+  isPrimaryCTA?: boolean;
+  isPinned?: boolean;
+  onClick: () => void;
+  disabled?: boolean;
+  hotkeys?: string[];
+};