Give the portal back the dropdown the CFP asked Audience level with

[EllAchE]

The post-submission edit view degrades and narrows the form. "Audience level" drops from a
Beginner/Intermediate/Advanced dropdown to a free-text input, so a speaker can save an arbitrary
string into a constrained field; and Session format, Track and Tags are not editable at all
(Track is read-only header text), leaving no self-service correction route for the fields
organizers filter and route on.

Flagged major by the call-for-papers judge. This PR is the first half — Audience level. Format,
Track and Tags are a follow-up, for the reason below.

What was wrong

submissionFields filters every built-in key out of what the portal editor renders, so the editor
hardcodes the built-ins it wants. level was hardcoded as an <Input> — an open text box for a
question the public form asks with a dropdown. submissionEditSchema then accepted any string up
to 60 characters into submission.level, which is what the review queue filters on and what the
exports group by. A speaker who typed anything at all put a value there that nothing else in the
product will ever match.

The fix

submissionLevelOptions(formId) reads what the form itself offers, falling back to the shared
DEFAULT_LEVELS when the field is present with no custom list. The editor renders a <Select> from
that, so an organizer who replaced the options gets their options, and a form whose organizer removed
the field renders nothing rather than an empty box.

The same rule server-side, in the exported pure levelError(value, options, current). The edit view
posts to a server action, and a server action takes whatever it is given; a <select> limits the
browser, not the request.

Two values pass that are not on the list, both because the old box let anything through:

• A blank. The question is optional, so clearing it is an answer.
• Whatever the record already says. A speaker fixing a typo in their title should not be blocked
  by a value they did not touch and cannot re-enter. The select offers that stored value too, so the
  page shows what the submission actually says instead of silently presenting the first option and
  saving it on the next edit. Moving off such a value is one-way, and levelError will not let it
  be applied to a different submission.

What this does not fix

Session format, Track and Tags remain uneditable. The judge filed both halves as one defect, but
they are different work: this one is data integrity on a column that already exists on the
submission row, while those three are missing capability — they need PortalSubmission extended
with formatId/trackId/tagIds, updateMySubmission extended to write them and to replace the
submission_tag rows, and the editor rendering their taxonomy options. One concern per PR, so that
is a follow-up rather than a bigger diff here.

Verification

bun run lint, bun run typecheck, bun run test (190 files, 2041 tests) and bun run build all
pass. bun run docs:openapi and bun run docs:mcp regenerate to no diff.

Eight new tests on levelError, covering both exceptions above, an organizer's own option list, and
a form that does not ask the question. The <Select> itself is not covered: this repo has no DOM
test tooling, so a rendered select's option list is not something a test here can inspect.

Part of the 2026-08-17T05-46-05 evaluation cycle. Not merged, not deployed.