feat: garden care reminder bodies, task sync, upload cleanup

- care reminders now fire with plant-specific body ("Time to water Pothos")
  via title/body columns on the reminders table (migration 0016)
- bi-directional task sync: checking off a garden-linked task list item
  creates a care log; logging care from garden marks the linked task done
  (list_items.metadata stores gardenPlantId + gardenCareType linkage)
- upload error response no longer leaks debug detail; error message
  corrected from "5 MB" to "100 MB"

drizzle/0016_garden_improvements.sql

@@ -0,0 +1,6 @@
+-- Add title/body to reminders for rich notification bodies
+ALTER TABLE reminders ADD COLUMN IF NOT EXISTS title text;
+ALTER TABLE reminders ADD COLUMN IF NOT EXISTS body text;
+
+-- Add metadata to list_items for garden task linking
+ALTER TABLE list_items ADD COLUMN IF NOT EXISTS metadata jsonb;