Surface speakers, recordings and contributing once the widget renders them #17

Blocked on OpenTechEvents/ote-tools#115. Nothing to do here until that ships.

Split out of #13, which is closed — everything reader-side in it is merged
(0.11.0). This is the remainder, which is one concrete job rather than a list
of findings.

Why it is blocked

The reader renders nothing itself: it sets widget.events on <ote-events>
and the widget draws every field. inherit() copies whole event objects, so
the data below already reaches the widget intact — there is no reader-side
change that would make any of it appear.

The widget targets OTE 0.4.0 (oteSpecVersion in its package.json), so
the four fields 0.5 added are unrendered and the one breaking change 0.5 made
(D032 pricing) is not applied. Note the widget's version line is not the
spec's: v0.8.2 is the current widget and still targets spec 0.4.0.

Already live data, waiting on this: 2 of CoruñaJUG's 11 events publish
speakers and nothing shows them.

What to do here once it ships

1. Bump the pinned widget in index.html (/embed/vX.Y.Z/), following
   the checklist in CLAUDE.md — check the widget's source for the attributes
   and properties this app sets, then verify in a browser.
2. Add the new field toggles to EVENT_FIELD_OPTIONS in app.js, with
   Spanish labels. That list mirrors the widget's ALL_FIELDS and is
   currently the ten it exposes:
   image, when, location, attendance, description, price, tags, organizer, cfp, eligibility.
   Candidates, depending on what upstream adds: speakers, recordings,
   contributing.
3. Re-verify pricing against a real multi-part feed if one exists by then.
   D032 needs no reader-side change — partOf already passes through — but it
   is the one of the four whose breakage produces a wrong answer rather than
   a missing one (a paid talk reading as free), so it is worth confirming with
   real data rather than assuming.
4. Changelog entry and version bump, per CLAUDE.md.

Not in scope

feed.covers is done (#15): a saved event is kept rather than resolved
against the live feed, and covers decides whether its absence is reported as
a withdrawal.