feat(handover): one hand-over sheet replaces the separate sale/plantare doors

'Seeds changed hands' is now the single entry point on the variety
detail (and per lot row): direction (gave/received), one-tap 'all of it'
(default — the whole-plant/shrub case), optional partial quantity,
counterparty, and reveal-on-tap money and return-promise sections that
spawn the Sale/Plantare rows through recordHandover in one save.

Zero-lot varieties still work (ledger rows only); several lots get a
chip picker. The Sales/Plantares screens keep their own add buttons for
off-app records — the sheets stay, demoted to secondary.

i18n handover block in en/es/pt/ast; widget tests for the flow.

apps/app_seeds/lib/i18n/en.i18n.json

@@ -622,6 +622,19 @@
     "settledSection": "Done",
     "removeConfirm": "Remove this commitment?"
   },
+  "handover": {
+    "title": "Seeds changed hands",
+    "help": "A gift, a swap or a sale — note it down, with a return promise or without.",
+    "iGave": "I gave seeds",
+    "iReceived": "I received seeds",
+    "whichLot": "Which batch?",
+    "howMuch": "How much?",
+    "allOfIt": "All of it",
+    "partOfIt": "A part",
+    "paymentChip": "Money changed hands",
+    "promiseGave": "They'll return me seed",
+    "promiseReceived": "I'll return seed"
+  },
   "sale": {
     "title": "Sales",
     "help": "Record seed you sold or bought — money, Ğ1, or any currency. A separate model from a gift or a Plantare. No commission is ever taken on seeds.",