Add Known Limitations for ListElement, Delegate Creation, and Virtual Keyboard to QML Type Compiler

I have identified three additional constraints related to the QML Type Compiler (qmltc) that are not yet documented under Known Limitations. Although the last one is partially noted, most new Qt users would have trouble realizing that the Virtual Keyboard (VKB) is also unsupported by qmltc. Given the impact on typical QML usage, these constraints should be explicitly mentioned.

1. Link Errors When Using ListElement

• • Issue: Including ListElement in a QML file compiled by qmltc leads to link-time errors referencing QQmlListElement::qt_metacast, qt_metacall, and staticMetaObject.
  • Reference: QTBUG-134206

1. Delegates Not Fully Compiled With QMLTC

• • Issue: When Repeater, ListView, or any other QML element uses a delegate, qmltc does not compile the delegate types into native code. Consequently, the "Creating" phase still appears in the QML Profiler, indicating runtime creation instead of using precompiled artifacts.
  • Reference: QTBUG-134206

1. Virtual Keyboard (VKB) Doesn't Work With QMLTC

• • Issue: Using VKB with qmltc leads to build errors.
  • Minimal Reproduction: vkb_issue
  • Note: No Jira ticket has been created, as this was discussed in a separate context.

Because these three constraints significantly affect real-world QML projects—especially those relying on ListModel/ListElement, delegates, or the Virtual Keyboard—I propose adding explicit warnings and details about them to the Known Limitations section in the qmltc documentation. This would help developers understand and navigate these issues more effectively.

Thank you for your attention and for all the hard work on Qt. If you need any further information, please let me know.