feat(plantare): surface product link + dates; spec the bilateral record

The Plantaré screen stored madeOn/dueBy/varietyId but showed none of them,
so it felt half-built. Surface what's already there (no schema change):

- watchPlantareViews() joins each commitment with its variety label
- tile shows the made-on date, a "Return by {date}" line (amber + "overdue"
  when an open promise is past due, via new seedWarning colour), the variety
  name, and taps through to /variety/:id
- add sheet gains an optional return-by date picker (createPlantare already
  took dueBy)
- variety detail shows a read-only commitments section (hidden when empty,
  no add button — honours the single hand-over door)
- i18n en/es/pt/ast; tests for the join, dueBy round-trip, tile, and section

Also specs the deferred two-sided record in docs/design/plantare-bilateral.md
(Nostr pubkey counterparty, PlantareTransport propose->accept->counter-sign,
deferred key/signature/movement columns, provenance DAG, reputation anchor),
with a faithful transcription of the paper Plantaré v0.4 (BAH-Semillero 2009,
CC-BY-SA). Cross-linked from data-model §2.7 and sharing-model §6.

docs/design/data-model.md

@@ -151,6 +151,11 @@ The digital version of the paper Plantare. Bilateral, signed, held by both parti
 | `debtor_signature` / `creditor_signature` | TEXT | Cryptographic signatures (both stubs of the paper). |
 | `status` | enum | `open` / `returned` / `forgiven`. Framed as a promise, not a debt (microcopy). |
 
+> **Shipped vs. planned.** `app_seeds` ships the local, one-sided version (variety link +
+> dates + `direction`/`counterparty` free text); the key/signature/`movement_id` columns
+> and the two-party handshake are **deferred**. Full spec of the bilateral signed record:
+> [plantare-bilateral.md](plantare-bilateral.md).
+
 ### 2.8 `Offer` — a published, discoverable listing
 The *shop window*: a signed statement published to the network so others can discover what you share. Distinct from `Lot` on purpose — publishing reveals only what you choose (privacy). Serializes to Nostr NIP-99 (`kind:30402`) or ActivityPub. Full rationale in [sharing-model.md](sharing-model.md).