Social composer: send now and rename messy account names (#6)

## Summary
Closes #5.
- Composer can **Send now** without a schedule time (Schedule and Save draft still available)
- Account names wrap and show the platform id so a bad OAuth label is still readable
- Social accounts page can rename the display name; re-auth keeps a custom name instead of overwriting it with a placeholder
- Worker polls `dispatch_due` every 15s so scheduled campaigns and social posts fire without a manual command; local `docker compose up` now starts the worker

## Test plan
- [ ] Open Social → Compose: confirm **Send now**, **Schedule**, and **Save draft** buttons (no combined Save / publish)
- [ ] Send now with a connected account and caption → post queues immediately, no datetime required
- [ ] Schedule with a datetime → post is scheduled; Schedule with a blank time → validation error
- [ ] Composer account list shows full name plus external id, wrapping if the name is long
- [ ] Social accounts → rename a messy label → new name shows in composer without reconnecting
- [ ] Re-authorize an account that was renamed → custom name is kept
- [ ] Rebuild and start compose (`docker compose up --build`) so the **worker** service is running
- [ ] Schedule a social post ~2 minutes ahead → after due time, worker logs `Enqueued N due item(s).` and the post leaves Scheduled (published or failed)
- [ ] `docker compose logs -f worker` shows `Polling due scheduled work every 15s.`

Reviewed-on: #6

site/core/management/commands/dispatch_due.py

@@ -1,3 +1,5 @@
+import time
+
 from django.core.management.base import BaseCommand
 from django.utils import timezone
 
@@ -10,10 +12,37 @@ from social.tasks import publish_social_post
 class Command(BaseCommand):
     help = (
         "Enqueue due scheduled campaign messages and social posts. "
-        "Optional when the task backend supports run_after defer; useful as a safety net."
+        "Pass --loop to poll until stopped (worker entrypoint)."
     )
 
+    def add_arguments(self, parser):
+        parser.add_argument(
+            "--loop",
+            action="store_true",
+            help="Poll forever until SIGINT/SIGTERM.",
+        )
+        parser.add_argument(
+            "--interval",
+            type=int,
+            default=15,
+            help="Seconds between polls when --loop is set (default 15).",
+        )
+
     def handle(self, *args, **options):
+        self.verbosity = int(options.get("verbosity", 1))
+        if options["loop"]:
+            interval = max(1, int(options["interval"] or 15))
+            self.stdout.write(f"Polling due scheduled work every {interval}s.")
+            try:
+                while True:
+                    self._dispatch_once()
+                    time.sleep(interval)
+            except KeyboardInterrupt:
+                self.stdout.write("dispatch_due loop stopped.")
+                return
+        self._dispatch_once()
+
+    def _dispatch_once(self):
         now = timezone.now()
         enqueued = 0
 
@@ -35,4 +64,7 @@ class Command(BaseCommand):
             publish_social_post.enqueue(post_id=str(post.pk))
             enqueued += 1
 
-        self.stdout.write(self.style.SUCCESS(f"Enqueued {enqueued} due item(s)."))
+        if enqueued:
+            self.stdout.write(self.style.SUCCESS(f"Enqueued {enqueued} due item(s)."))
+        elif self.verbosity >= 2:
+            self.stdout.write("No due items.")