feat: collections overhaul — reorder, search, edit/delete, tags (v0.53.0)

Seven related improvements to collections:

- Drag-and-drop reorder (dnd-kit, same pattern as the shopping list) — new
  collection_recipes.position column (migration 0049, backfilled from
  existing added_at order so nothing jumps around on upgrade).
- Search collections by name/description (server-side, list page) and
  search recipes within a collection (client-side filter, already loaded).
- Edit collection: name/description/tags/private notes via a new dialog;
  new collections.notes + collections.tags columns.
- Delete collection with a choice to also delete its recipes — only ones
  the deleting user actually owns, never recipes shared in by others.
- Collection detail (both owner and public view) now renders the same
  RecipeGridCard used on /recipes, instead of the older, plainer RecipeCard.
- Collection list cards redesigned — photo-collage preview (first 4 recipe
  covers/placeholders), tag badges, cleaner layout.
- Fixed the recipe count shown on a collection card: the query capped the
  `recipes` relation at 1 for thumbnail purposes and then read `.length`
  off that same capped array, so it never showed more than 1. Now a
  proper grouped count query, separate from the thumbnail fetch.

New/changed endpoints documented in OpenAPI: PATCH /collections/{id}/reorder,
DELETE /collections/{id}?deleteRecipes, PUT /collections/{id}'s new
notes/tags fields.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

packages/db/src/schema/social.ts

@@ -61,6 +61,8 @@ export const collections = pgTable("collections", {
   userId: text("user_id").notNull().references(() => users.id, { onDelete: "cascade" }),
   name: text("name").notNull(),
   description: text("description"),
+  notes: text("notes"),
+  tags: text("tags").array().notNull().default([]),
   isPublic: boolean("is_public").notNull().default(false),
   createdAt: timestamp("created_at").notNull().defaultNow(),
   updatedAt: timestamp("updated_at").notNull().defaultNow(),
@@ -71,8 +73,11 @@ export const collections = pgTable("collections", {
 export const collectionRecipes = pgTable("collection_recipes", {
   collectionId: text("collection_id").notNull().references(() => collections.id, { onDelete: "cascade" }),
   recipeId: text("recipe_id").notNull().references(() => recipes.id, { onDelete: "cascade" }),
+  position: integer("position").notNull().default(0),
   addedAt: timestamp("added_at").notNull().defaultNow(),
-});
+}, (t) => [
+  index("collection_recipes_collection_position_idx").on(t.collectionId, t.position),
+]);
 
 export const collectionFavorites = pgTable("collection_favorites", {
   userId: text("user_id").notNull().references(() => users.id, { onDelete: "cascade" }),