Fix worker stuck on "Working..." and default channels to disabled

1. Worker trigger: Add ingestion_trigger pg_notify listener so the worker
   picks up on-demand triggers from the UI and runs an immediate cycle with
   full activity tracking (currentActivity, currentStep, etc).

2. Remove orphaned IngestionRun creation from triggerIngestion server action.
   Previously the UI created RUNNING runs without activity fields, causing
   the UI to show "Working..." with no details. Now only the worker creates
   runs with proper activity tracking.

3. Default channels to disabled (isActive: false) in schema and all creation
   paths. Destination channels are explicitly set to active since they must
   receive uploads. Includes Prisma migration.

Co-authored-by: xCyanGrizzly <53275238+xCyanGrizzly@users.noreply.github.com>

worker/src/db/queries.ts

@@ -302,11 +302,15 @@ export interface UpsertChannelInput {
   title: string;
   type: "SOURCE" | "DESTINATION";
   isForum: boolean;
+  isActive?: boolean;
 }
 
 /**
  * Upsert a channel by telegramId. Returns the channel record.
  * If it already exists, update title and forum status.
+ * New channels default to disabled (isActive: false) so the admin must
+ * explicitly enable them before the worker processes them.
+ * Pass isActive: true for DESTINATION channels that must be active immediately.
  */
 export async function upsertChannel(input: UpsertChannelInput) {
   return db.telegramChannel.upsert({
@@ -316,6 +320,7 @@ export async function upsertChannel(input: UpsertChannelInput) {
       title: input.title,
       type: input.type,
       isForum: input.isForum,
+      isActive: input.isActive ?? false,
     },
     update: {
       title: input.title,