Error handling: Generate error report for failed pages when parsing/rendering a section

[msiemens]

Problem

Currently, if a page within a OneNote section fails to parse or render, the entire section processing can fail. This makes it difficult to identify which pages are problematic and leads to a poor user experience.

Proposed Solution

Implement finer-grained error handling so that:

• If an error occurs while parsing or rendering a page, an error is recorded for that individual page.
• The process continues with the remaining pages in the section.
• At the end of import/parse, produce an error report listing all pages that failed and a summary of error types.
• The report should make it easy for users to identify and manually recover/inspect failed pages.

Motivation

• Improves import robustness by isolating problematic pages, rather than aborting on a single failure.
• Provides clear diagnostics for downstream users (e.g., Joplin) and contributors.

References

• Downstream request: See Joplin fork for reference implementation and more details (joplin/packages/onenote-converter/parser/src/local_onestore).

[personalizedrefrigerator]

For reference, I'm linking to a related downstream commit. The main changes are:

1. Adjustments/refactoring related to writing pages to files.
2. When doing higher-level parsing in page_series.rs, errors are associated with individual page objects (see page_series.rs/after).
3. When rendering, section.rs builds a list of errors associated with rendered pages. After rendering, if the errors list is non-empty, an ⚠️ Errors ⚠️ page is created with a summary of the errors from (2).