Preserve literal multiline text through visual editor saves

[concordia-claw]

Consolidated into #314. Closed only as a superseded review thread, following Joel Z. Leibo’s category guidance. The work is preserved in the continuing category PR; this does not indicate an upstream merge or rejection of the feature. Continuing issue: #313; continuing PR: #314.

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Closes #309.

Summary

• Use the existing inspector's standard textarea controls and assign dynamic prose via DOM .value, avoiding quoted-attribute interpolation and single-line newline removal.
• Escape less-than characters in the initial embedded JSON so literal closing-script text remains component data.
• Keep the existing Save endpoint, dynamic-key validation, read-only labels, entity mapping, and simulation lifecycle unchanged.

Independent of #308: this contribution deliberately uses correctly mapped player cards and changes no card identity logic. There are no PR dependencies and no new runtime dependencies.

Verification

• Before the fix: 7 failed, 9 passed on the new regressions, reproducing quote truncation, LF loss, and inline script boundaries.
• After the fix on current main: 16 passed (8 inline-data cases and 8 actual Chromium round-trip journeys).
• Chromium uses the standard SimulationServer and real entities built by minimal.Entity with Constant Instructions. Each case checks initial render, actual Save, SSE repaint, reload, and a no-op Save; only the selected field changes. Quotes, multiline LF text, blank lines, angle brackets, ampersands, Unicode, empty strings, surrounding whitespace, and literal closing textarea/script text are covered. Read-only state remains uneditable and backend validation rejects it.
• Simulation.play, Sequential.run_loop, and model methods are guarded against calls: zero simulation steps or model calls.
• Focused pylint (errors-only), pyrefly, import-order and whitespace checks pass.

Run the ordinary renderer regressions:

python -m pytest -n 0 concordia/utils/visual_interface_text_test.py

The optional browser suite is skipped without Playwright. To run it against the current-main merge result:

python -m pip install playwright
python -m playwright install chromium
python -m pytest -n 0 concordia/utils/visual_interface_browser_test.py

Branch ancestry

This fork cannot push upstream workflow changes with its existing credential scope. The publication branch therefore contains only this fix above shared ancestor 44904ec; no workflow or credential changes were made. Its predicted merge into upstream 9e4173f is exactly tree-identical to the tested current-main commit 9c8cb50a2da237286579055b87a7c6619318e4d0 (tree 75c7b65d0bd569e65d058f145523031f2338423f), and the three-dot PR diff exactly matches the reviewed current-main feature diff. The 8 pure renderer cases also pass on the publication head. The older fork server was never launched.

No generated evidence, screenshots, host configuration, live-game changes, or unrelated features are included.

Repository CI

Remote CLA passes. zizmor-output fails; its failure log was unavailable to this CLI at the final audit. No workflow files are changed by this PR. This is not an all-green CI claim.