Get Deal Detail

Detail for ONE deal. Two callers, two projections:

1. DEFAULT (heavy fields only) — DealDetailDialog on card open. The dialog already has the light fields from the board list row and useDealDetailMerge merges the detail fields on top (the live list row wins on every overlap), so we don't re-send the light fields — the common path stays lean. No annotate chain re-run. sales_plan IS in this shape: it is not a light field the row can be trusted for (a shape=card row holds only the projected next action), so the dialog always gets the canonical full plan from here.
2. ?full=true (whole deal) — the deep-link fallback (PipelineKanbanView) for an off-board deal: a ?deal=<id> link to a dismissed / non-visible deal NOT in the board's fetched set. There is no list row to merge onto, so the dialog renders this response directly and needs the full deal.

Org/RLS-scoped exactly like the sibling routes; no review_state filter (a dismissed deal is returned). Registered AFTER the static /deals and /deals/pending GETs so {deal_id} never captures them.