refactor: fix naming, remove duplicate code from decomposition

- Rename _int_or_default → int_or_default (public API, was using private convention)
- Extract shared pdf_queue utilities (utcnow, event_row, queued_job, status constants) to pdf_queue_common.py to avoid circular imports
- Consolidate _effective_request_delay_seconds into queue_runner.py with explicit floor parameter
- Update tests to match new function locations and names

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/services/publications/pdf_queue_common.py

@@ -0,0 +1,49 @@
+from __future__ import annotations
+
+from datetime import UTC, datetime
+
+from app.db.models import PublicationPdfJob, PublicationPdfJobEvent
+
+PDF_STATUS_QUEUED = "queued"
+PDF_STATUS_RUNNING = "running"
+PDF_STATUS_RESOLVED = "resolved"
+PDF_STATUS_FAILED = "failed"
+
+
+def utcnow() -> datetime:
+    return datetime.now(UTC)
+
+
+def event_row(
+    *,
+    publication_id: int,
+    user_id: int | None,
+    event_type: str,
+    status: str | None,
+    source: str | None = None,
+    failure_reason: str | None = None,
+    message: str | None = None,
+) -> PublicationPdfJobEvent:
+    return PublicationPdfJobEvent(
+        publication_id=publication_id,
+        user_id=user_id,
+        event_type=event_type,
+        status=status,
+        source=source,
+        failure_reason=failure_reason,
+        message=message,
+    )
+
+
+def queued_job(
+    *,
+    publication_id: int,
+    user_id: int,
+) -> PublicationPdfJob:
+    now = utcnow()
+    return PublicationPdfJob(
+        publication_id=publication_id,
+        status=PDF_STATUS_QUEUED,
+        queued_at=now,
+        last_requested_by_user_id=user_id,
+    )