feat(timer): allow swapping the secondary source into the main timer slot

The timer view lets operators show an aux timer or the secondary message
as a smaller secondary timer under the main event timer. This adds a
placement control so that selected source can be promoted into the main
slot, swapping positions with the event timer.

The swap is deliberate: the event timer is demoted to the secondary slot
rather than removed, so the show-critical countdown (and its phase colour)
is never lost from screen.

- add `SecondaryPlacement` ('below' | 'main') to the timer message, with
  server validation and a store default
- expose the aux timer direction to the timer view and honour it when
  formatting a promoted aux (previously hard-coded to count-down)
- add a `getTimerSlots` helper that assigns the event timer and secondary
  content to the main/secondary slots, routing phase colour, paused/finished
  styling and font sizing to whichever slot holds the event timer
- add a Placement radio control to the timer view panel (disabled until a
  secondary source is active) and reflect the swap in the control preview

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MbgWVAXTJUX7E5pAmv6Rs7

packages/types/src/definitions/runtime/MessageControl.type.ts

@@ -1,11 +1,19 @@
 export type SecondarySource = 'aux1' | 'aux2' | 'aux3' | 'secondary' | null;
 
+/**
+ * Where the selected secondary source is displayed in the timer view
+ * - below: shown as a smaller timer under the main timer (default)
+ * - main: swapped into the main slot, demoting the event timer to the secondary slot
+ */
+export type SecondaryPlacement = 'below' | 'main';
+
 export type TimerMessage = {
   text: string;
   visible: boolean;
   blink: boolean;
   blackout: boolean;
   secondarySource: SecondarySource;
+  secondaryPlacement: SecondaryPlacement;
 };
 
 export type MessageState = {

packages/types/src/definitions/runtime/RuntimeStore.ts

@@ -24,6 +24,7 @@ export const runtimeStorePlaceholder: Readonly<RuntimeStore> = {
       blink: false,
       blackout: false,
       secondarySource: null,
+      secondaryPlacement: 'below',
     },
     secondary: '',
   },

packages/types/src/index.ts

@@ -108,7 +108,12 @@ export type { ApiAction, ApiActionTag, ApiResponse } from './api/websocket/api.t
 export { type Log, LogLevel, type LogMessage, LogOrigin } from './definitions/runtime/Logger.type.js';
 export { Playback } from './definitions/runtime/Playback.type.js';
 export { TimerLifeCycle, timerLifecycleValues } from './definitions/core/TimerLifecycle.type.js';
-export type { TimerMessage, MessageState, SecondarySource } from './definitions/runtime/MessageControl.type.js';
+export type {
+  TimerMessage,
+  MessageState,
+  SecondarySource,
+  SecondaryPlacement,
+} from './definitions/runtime/MessageControl.type.js';
 
 export type { RundownState } from './definitions/runtime/RundownState.type.js';
 export type { Offset } from './definitions/runtime/Offset.type.js';