Use PTX genreated chapter numbers when processing manifest

[ascholerChemeketa]

Fix for #1310

[Copilot]

Pull request overview

This PR addresses Runestone issue #1310 where assignment reading chapter numbers are off by one, by switching chapter/subchapter numbering to use the PreTeXt (PTX) manifest-provided <number> values rather than purely sequential counters.

Changes:

• Use manifest <number> for chapters.chapter_num when processing chapters.
• Parse manifest subchapter numbers like "1.1" to store/display only the subchapter portion (e.g., "1").
• Rename internal counters for clarity (chapter_counter, subchap_counter).

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[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (2)

components/rsptx/build_tools/core.py:694

• chapter.find("./number").text can raise AttributeError when the <number> element is missing, and int(cnum_text) can raise ValueError if the manifest contains whitespace or a non-integer value. Since the code already has a fallback to the counter, it should safely read and parse the text (including stripping) and fall back on parse errors.

    cnum_text = chapter.find("./number").text
    if not cnum_text:
        cnum = chap_counter
    else:
        cnum = int(cnum_text)

components/rsptx/build_tools/core.py:756

• subchapter.find("./number").text can raise AttributeError if the <number> element is missing, and the int() conversion will raise if the value includes unexpected whitespace or a non-integer (e.g., malformed x.y). Use findtext() + strip() and fall back to subchap_counter on parse errors to avoid failing the whole manifest load.

    scnum_text = subchapter.find("./number").text
    if scnum_text:
        # subchapter numbers are in manifest as "1.1", "1.2", etc.
        # strip off the chapter number and just keep the subchapter number
        if "." in scnum_text:

[ascholerChemeketa]

Pushed with updates for Copilot review