OpenSystemsDevelopment / qpdf

…e includes, and streamline page-related logic.

…gin`/`end` methods, update calls across codebase, and streamline page handling logic.

…che`, update calls, streamline initialization, and enhance assertion usage.

…` to `Pages`, update methods to use relocated fields, and streamline cache handling.

…::removePage` to use `Pages::erase`, streamline cache handling in `Pages::update_cache`.

…ges::all` method, add `Pages::size` and `empty` methods, move `getAllPagesInternal` to private section, streamline encapsulation, and enhance code organization.

… to improve code organization.

… streamline error handling, and improve encapsulation.

… improve encapsulation.

…nd improve encapsulation.

…s, and improve encapsulation.

…ctions and improve encapsulation.

Refactor stream copying

…reamline stream registration, and improve encapsulation.

… and streamline stream handling.

… handling, and enhance encapsulation.

…tion, and streamline stream registration logic.

…ta`and streamline foreign stream handling.

…oreign stream handling, and simplify return logic.

…e encapsulation, and streamline foreign stream handling.

…prove encapsulation, and streamline stream data handling.

…e encapsulation, and streamline stream data handling.

Refactor foreign object copying

…eamline foreign object handling, and simplify method structure.

…`Copier` usage, and simplify object copying logic.

…ne object copying logic, and simplify method structure.

…object reservation, and streamline method usage.

…rect_object`, simplify object replacement, and streamline method usage.

…eamline type-specific handling, and remove redundant test coverage evaluations.

…t usage of `std::shared_ptr`, simplify stream data management, and enforce `final` specifier.

… `StreamDataProvider` management.