Address Gadfly review on #8: modal focus/close, dim validation, dedup

Fixes from the PR #27 adversarial review (considered; not graded).

Correctness / error-handling
- Modal: focus once on mount and attach the keydown listener once (latest
  onClose/busy via refs), so a parent re-render (e.g. a background refetch)
  no longer re-fires focus() and steals it from the input being typed in.
- Modal takes a `busy` prop; while a save/delete is in flight, Escape and
  backdrop clicks don't dismiss it (form/delete modals pass busy=pending),
  so an action can't be interrupted mid-flight and lose its error.
- Form validates the *converted* centimeter values against the server's
  [1cm, 100m] bounds, so sub-cm / over-100m sizes fail client-side with a
  clear message instead of a generic server error.
- displayFromCm rounds imperial to 0.1 ft so an 8 ft garden (244 cm)
  prefills as "8", not "8.01".

Maintainability
- Extracted ui/field.ts (useFieldId + fieldControlClass) shared by
  TextField/TextArea/Select. Added a `danger` Button variant, used by the
  delete modal; card edit/delete buttons gained focus-visible rings.
- useUpdateGarden takes the id in its mutation variables (no dummy 0 during
  create). GardensPage shares a close handler; dropped a redundant zod
  annotation; 409 rebase reuses dimString; renamed `del` -> `deletion`.

Verified in a browser: 8 ft round-trips to a prefilled "8"; a sub-cm value
is rejected client-side with the modal staying open. tsc clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01JdQpdYYsTgtkJBxbcpAszi

web/src/components/gardens/GardenFormModal.tsx

@@ -7,7 +7,13 @@ import { TextArea } from '@/components/ui/TextArea'
 import { TextField } from '@/components/ui/TextField'
 import { errorMessage } from '@/lib/api'
 import { conflictGarden, useCreateGarden, useUpdateGarden, type Garden } from '@/lib/gardens'
-import { cmFromDisplay, dimensionUnitLabel, displayFromCm, type UnitPref } from '@/lib/units'
+import {
+  cmFromDisplay,
+  dimensionUnitLabel,
+  displayFromCm,
+  isValidDimensionCm,
+  type UnitPref,
+} from '@/lib/units'
 
 const DEFAULT_METERS = 10 // matches the server's 10 m default
 
@@ -29,7 +35,7 @@ function dimString(cm: number | undefined, unit: UnitPref): string {
 export function GardenFormModal({ garden, onClose }: { garden?: Garden; onClose: () => void }) {
   const isEdit = !!garden
   const create = useCreateGarden()
-  const update = useUpdateGarden(garden?.id ?? 0)
+  const update = useUpdateGarden()
   const pending = create.isPending || update.isPending
 
   const [name, setName] = useState(garden?.name ?? '')
@@ -56,24 +62,25 @@ export function GardenFormModal({ garden, onClose }: { garden?: Garden; onClose:
     setFormError(null)
     setConflict(null)
 
-    const w = parseFloat(width)
-    const h = parseFloat(height)
-    if (!name.trim() || !Number.isFinite(w) || w <= 0 || !Number.isFinite(h) || h <= 0) {
-      setFormError('Enter a name and a positive width and height.')
+    if (!name.trim()) {
+      setFormError('Enter a name for the garden.')
+      return
+    }
+    // Validate the converted centimeter values against the same bounds the
+    // server enforces, so sub-cm or over-100m sizes fail here with a clear
+    // message instead of a generic server error.
+    const widthCm = cmFromDisplay(parseFloat(width), unit)
+    const heightCm = cmFromDisplay(parseFloat(height), unit)
+    if (!isValidDimensionCm(widthCm) || !isValidDimensionCm(heightCm)) {
+      setFormError('Width and height must be between 1 cm and 100 m.')
       return
     }
 
-    const input = {
-      name: name.trim(),
-      widthCm: cmFromDisplay(w, unit),
-      heightCm: cmFromDisplay(h, unit),
-      unitPref: unit,
-      notes: notes.trim(),
-    }
+    const input = { name: name.trim(), widthCm, heightCm, unitPref: unit, notes: notes.trim() }
 
     try {
       if (isEdit) {
-        await update.mutateAsync({ ...input, version })
+        await update.mutateAsync({ id: garden.id, ...input, version })
       } else {
         await create.mutateAsync(input)
       }
@@ -86,8 +93,8 @@ export function GardenFormModal({ garden, onClose }: { garden?: Garden; onClose:
         setVersion(current.version)
         setName(current.name)
         setUnit(current.unitPref)
-        setWidth(String(displayFromCm(current.widthCm, current.unitPref)))
-        setHeight(String(displayFromCm(current.heightCm, current.unitPref)))
+        setWidth(dimString(current.widthCm, current.unitPref))
+        setHeight(dimString(current.heightCm, current.unitPref))
         setNotes(current.notes)
         setConflict('This garden changed elsewhere. The latest values are shown — review and save again.')
         return
@@ -99,7 +106,7 @@ export function GardenFormModal({ garden, onClose }: { garden?: Garden; onClose:
   const unitLabel = dimensionUnitLabel(unit)
 
   return (
-    <Modal title={isEdit ? 'Edit garden' : 'New garden'} onClose={onClose}>
+    <Modal title={isEdit ? 'Edit garden' : 'New garden'} onClose={onClose} busy={pending}>
       <form onSubmit={onSubmit} className="flex flex-col gap-3">
         {conflict && <Alert tone="info">{conflict}</Alert>}