feat(pipelines): add custom processing pipeline engine

- Add Pipeline and PipelineStep models with user-specific ownership
- Add pipeline_id FK column to FileRecord
- Migration 017_add_pipelines (batch mode for SQLite FK compat)
- Pipeline CRUD API at /api/pipelines with step management endpoints
- Reorder steps PUT endpoint placed before parameterised {step_id} routes
- POST /api/files/{id}/assign-pipeline for per-file pipeline assignment
- Admin-only POST /api/pipelines/admin/system for system-level pipelines
- Management UI at /pipelines (Jinja2 + Alpine.js + Tailwind)
- Pipelines link added to desktop and mobile navigation
- 41 new tests in tests/test_api_pipelines.py (all passing)

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

app/views/__init__.py

@@ -14,6 +14,7 @@ from app.views.general import router as general_router
 from app.views.google_drive import router as google_drive_router
 from app.views.license_routes import router as license_router  # Add the license router
 from app.views.onedrive import router as onedrive_router
+from app.views.pipelines import router as pipelines_router  # Processing pipelines
 from app.views.plans import router as plans_router  # Admin Plan Designer
 from app.views.queue import router as queue_router
 from app.views.search import router as search_router
@@ -39,3 +40,4 @@ router.include_router(search_router)
 router.include_router(queue_router)
 router.include_router(subscriptions_router)  # Pricing + subscription pages
 router.include_router(plans_router)  # Admin Plan Designer
+router.include_router(pipelines_router)  # Processing pipelines