GA flags titles as sentence fragments

# GA flags titles as sentence fragments

The Grading Assistant treats the title line of an essay like a regular sentence and flags it as a fragment when it (correctly) doesn't form a complete sentence.

## Reproduction

1. As a student, write an essay with a title that is a noun phrase (normal title behavior).
2. Submit and run GA.
3. Observe GA marks the title with a fragment warning.

Specific example noted: a title written in lowercase with a trailing period got flagged as a fragment instead of being coached to capitalize and drop the period.

## Expected

GA recognizes titles and either ignores them for fragment-checking purposes or coaches good titling (capitalization, no trailing punctuation, etc.). Connects to [features/title-coaching.md](../features/title-coaching.md).

## Actual

GA applies sentence-fragment grammar checks to the title line.

## Impact

Wrong feedback signal. Distracts from real grammar issues elsewhere in the essay. Reported 2026-02-27.

## Suspected cause

GA prompt or pipeline doesn't distinguish a title element from a body sentence. Tag the title in the document model so the GA can treat it as a title.

## Workaround

Teachers can tell students to ignore the false flag. Not ideal.