feat(entries): rotating partners — pair individuals who are already paired, in an AD_HOC draw

[CourtHive]

⚠️ Merge only after TMX's factory pin includes #4903(factory)

TMX pins tods-competition-factory@6.38.0 (latest published). #4890/#4891/#4903(factory), which let AD_HOC draws hold pairs sharing an individual and keep one person out of two matchUps of a round, are on factory dev and unreleased. With this toggle on 6.38.0, DrawMatic can schedule one person in two matchUps at once. CI resolves the published package, so it will not show this. Hence draft.

Why

AD_HOC entries are a roster, not a field: one person partnering several others over an evening is legitimate, and the factory now permits it only there. TMX had no way to create such a pair. An individual who is already paired is not an entry, so they never appeared in the table to be selected. The only route was destroying pairs.

What

In the draw-entries view of an AD_HOC doubles draw (DrawMatic included; never SWISS, never the event view) there is a Rotating partners toggle:

Default	not persisted; starts ON when the draw already holds pairs sharing an individual
[Grouped] rows	each individual of the draw's PAIR entries, as a virtual row (outlined chip, "with " under the name). Never an entry; pairing only
Ungrouped rows	also the event's UNGROUPED individuals not yet in the draw, so they can be paired into it
Pairing	Grouped+Grouped and Grouped+Ungrouped. Existing partners are refused (pairFromUnified allows duplicate participant pairs, so the factory would not stop it)
Entry placement	a pair sharing an individual enters the draw as the chosen segment and the event as ALTERNATE, so a bracketed flight generated from the event's accepted entries is not refused for the overlap. A non-overlapping pair is added exactly as before
Other actions	Move / Remove from draw / etc. are withheld from any selection containing a Grouped or event-only row

Every decision lives in the DOM-free rotatingPartners.ts.

Also fixed (found by the journey): navigating between entries views before Tabulator finished building left a stale panel whose tableBuilt called insertBefore on a detached container (page error) and could repaint EVENT_CONTROL with its own items. Stale panels now return early. Without the guard the error fired 1 run in 1; with it, 0 in 4.

Evidence

• rotatingPartners.test.ts: 12 tests, including the overlapping-pair plan executed against the factory (pair lands in the AD_HOC draw as DIRECT_ACCEPTANCE, event ALTERNATE, SINGLE_ELIMINATION still generates).
• Journey 125 (3 tests) against a dev server built from this branch + factory dev @ d3c0e5a84: toggle defaults, Grouped count, existing partners refused, Grouped+Grouped pair, event-ungrouped+Grouped pair, reopen starts ON, no toggle on all-entries, no page errors. With journeys 19, 22, 23, 33, 123: 28 passed.
• check-types, lint, format:check, attr-audit --ci, i18n-audit --ci clean. vitest 184 files / 2,017 tests passed (baseline 2,005).