refactor: extract pagination engine and publication upsert from ingestion service

Split app/services/ingestion/application.py (2,955 lines) into three
focused modules:

- page_fetch.py (219 lines): PageFetcher class for single-page fetch,
  parse-or-layout-error handling, and retry with backoff
- pagination.py (486 lines): PaginationEngine class for multi-page
  orchestration, loop state management, and short-circuit detection
- publication_upsert.py (239 lines): module-level functions for
  resolve_publication, upsert_profile_publications, and all
  find/create/update helpers

Also fixes two external import paths in portability/ that incorrectly
sourced normalize_title and build_publication_url from application.py
instead of fingerprints.py.

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

app/services/portability/normalize.py

@@ -3,7 +3,7 @@ from __future__ import annotations
 import hashlib
 from typing import Any
 
-from app.services.ingestion.application import normalize_title
+from app.services.ingestion.fingerprints import normalize_title
 from app.services.portability.constants import (
     MAX_IMPORT_PUBLICATIONS,
     MAX_IMPORT_SCHOLARS,

app/services/portability/publication_import.py

@@ -7,7 +7,7 @@ from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.db.models import Publication, ScholarProfile, ScholarPublication
 from app.services.doi.normalize import normalize_doi
-from app.services.ingestion.application import build_publication_url, normalize_title
+from app.services.ingestion.fingerprints import build_publication_url, normalize_title
 from app.services.portability.normalize import (
     _normalize_citation_count,
     _normalize_optional_text,