Agent: catalog and garden tools, and a ready date on every describe group

- update_seed_lot / delete_seed_lot: correct or drop a recorded purchase
  ("it was three packets, not two"); the plant a lot is for stays fixed.
- delete_plant: remove a duplicate from the user's catalog. The service
  already refuses while plantings (past seasons included) or a lot reference
  it; the tool turns that sentinel into words the model can pass on, and
  tells it not to clear those references to get its way.
- create_garden: a new place, with the service's defaults; the prompt says a
  plan is still a copy_garden.
- describe_garden groups carry readyAround — planting date plus days to
  maturity for the plops still in the ground — so "what can I pick this
  week?" is a lookup rather than arithmetic the model got wrong live.

Co-Authored-By: Claude Fable 5 <[email protected]>

internal/service/ops.go

@@ -7,6 +7,7 @@ import (
 	"log/slog"
 	"math"
 	"strings"
+	"time"
 
 	"gitea.stevedudenhoeffer.com/steve/pansy/internal/domain"
 )
@@ -614,6 +615,11 @@ type DescribeGroup struct {
 	// DaysToMaturity is the plant's, when the catalog knows it — with PlantedAt,
 	// enough to say when the harvest is due.
 	DaysToMaturity *int `json:"daysToMaturity,omitempty"`
+	// ReadyAround is that arithmetic done: planting date plus days to maturity
+	// for the plops still in the ground, as one date or "first…last". Absent
+	// when the catalog has no days for the plant or nothing is dated. The
+	// model was asked "what can I pick this week?" and got the sums wrong.
+	ReadyAround string `json:"readyAround,omitempty"`
 	// Removed counts the plops in the group that have been pulled, and RemovedAt
 	// is when ("first…last" when they differ). Only a season view lists pulled
 	// plops, so both are absent from a describe of what is growing now.
@@ -746,6 +752,15 @@ func describeGroups(o *domain.GardenObject, plops []domain.Planting, plantByID m
 			DaysToMaturity: plant.DaysToMaturity,
 			RemovedAt:      dateRangeOf(members, func(pl domain.Planting) *string { return pl.RemovedAt }),
 		}
+		if plant.DaysToMaturity != nil {
+			days := *plant.DaysToMaturity
+			g.ReadyAround = dateRangeOf(members, func(pl domain.Planting) *string {
+				if pl.RemovedAt != nil {
+					return nil // pulled already; its harvest is not ahead of us
+				}
+				return readyDate(pl.PlantedAt, days)
+			})
+		}
 		for _, pl := range members {
 			g.Plants += effectiveCount(pl)
 			if pl.RemovedAt != nil {
@@ -778,6 +793,20 @@ func describePlanting(pl domain.Planting, plantName string) DescribePlanting {
 	return d
 }
 
+// readyDate is plantedAt plus days to maturity, or nil when the plop is undated
+// (or its date is not one the store should have accepted).
+func readyDate(plantedAt *string, days int) *string {
+	if plantedAt == nil || *plantedAt == "" {
+		return nil
+	}
+	t, err := time.Parse(dateLayout, *plantedAt)
+	if err != nil {
+		return nil
+	}
+	d := t.AddDate(0, 0, days).Format(dateLayout)
+	return &d
+}
+
 // effectiveCount is the plant count a plop stands for: its explicit count, else
 // the one derived from its area and the plant's spacing.
 func effectiveCount(pl domain.Planting) int {