Address #125 review: memoized ink, one fallback color, reactive copy name

- monogramInk is memoized by color string; the canvas asks for every
  visible plop on every frame of a pan (Gadfly, 2/4 models).
- FALLBACK_PLANT_COLOR lives in lib/plants and is used by the canvas, the
  inspector and the garden thumbnail instead of three raw '#97a97c's.
- CopyDialog keeps its proposed "<base> — <year>" in step with the gardens
  list until the person edits the name, so a list that loads after the
  dialog opens can't leave a taken year in the field.
- GardenCard: reflowed the summary comment; no dead fallback on a plan
  name that's already known to parse.
- today() has one import path (lib/dates); the journal re-export is gone.
- CLAUDE.md says what the inspector actually does (a text-compare guard)
  rather than claiming it uses LengthField.

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

CLAUDE.md

@@ -134,7 +134,10 @@ Conventions that follow from it:
   a view, `cm` changes only when the person types. Never re-parse the display
   string on save — "29′ 6.3″" is the nearest tenth of an inch, and parsing it
   back is how a no-change Save turned 900 cm into 899.922 (and bumped the
-  version, and wrote a bogus history entry). The inspector guards the same way.
+  version, and wrote a bogus history entry). The inspector still keeps display
+  strings but gets the same result by refusing to commit text that still equals
+  the formatted original (`commitDim`); either way, a no-op save sends exactly
+  what was loaded — or nothing.
 - **"Today" is the browser's local day**, from `today()` in
   `web/src/lib/dates.ts`, and the UI always sends it: journal `observedAt`,
   plop/fill `plantedAt`, `removedAt`. The server's UTC default is only for