Add "data export" feature

- Adds a button in Account Settings where you can request a ZIP export of your
  Fizzy data
- Export files are created in the background. When ready, a link to
  download them is sent to the requester.
- Exports expire after 24 hours. And are limited to 10 per day.

db/migrate/20251201100607_create_account_exports.rb

@@ -0,0 +1,14 @@
+class CreateAccountExports < ActiveRecord::Migration[8.2]
+  def change
+    create_table :account_exports, id: :uuid do |t|
+      t.uuid :account_id, null: false
+      t.uuid :user_id, null: false
+      t.string :status, default: "pending", null: false
+      t.datetime :completed_at
+      t.timestamps
+
+      t.index :account_id
+      t.index :user_id
+    end
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.2].define(version: 2025_11_29_175717) do
+ActiveRecord::Schema[8.2].define(version: 2025_12_01_100607) do
   create_table "accesses", id: :uuid, charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.datetime "accessed_at"
     t.uuid "account_id", null: false
@@ -25,6 +25,17 @@ ActiveRecord::Schema[8.2].define(version: 2025_11_29_175717) do
     t.index ["user_id"], name: "index_accesses_on_user_id"
   end
 
+  create_table "account_exports", id: :uuid, charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.uuid "account_id", null: false
+    t.datetime "completed_at"
+    t.datetime "created_at", null: false
+    t.string "status", default: "pending", null: false
+    t.datetime "updated_at", null: false
+    t.uuid "user_id", null: false
+    t.index ["account_id"], name: "index_account_exports_on_account_id"
+    t.index ["user_id"], name: "index_account_exports_on_user_id"
+  end
+
   create_table "account_external_id_sequences", id: :uuid, charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.bigint "value", default: 0, null: false
     t.index ["value"], name: "index_account_external_id_sequences_on_value", unique: true

db/schema_sqlite.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.2].define(version: 2025_11_29_175717) do
+ActiveRecord::Schema[8.2].define(version: 2025_12_01_100607) do
   create_table "accesses", id: :uuid, force: :cascade do |t|
     t.datetime "accessed_at"
     t.uuid "account_id", null: false
@@ -25,6 +25,17 @@ ActiveRecord::Schema[8.2].define(version: 2025_11_29_175717) do
     t.index ["user_id"], name: "index_accesses_on_user_id"
   end
 
+  create_table "account_exports", id: :uuid, force: :cascade do |t|
+    t.uuid "account_id", null: false
+    t.datetime "completed_at"
+    t.datetime "created_at", null: false
+    t.string "status", limit: 255, default: "pending", null: false
+    t.datetime "updated_at", null: false
+    t.uuid "user_id", null: false
+    t.index ["account_id"], name: "index_account_exports_on_account_id"
+    t.index ["user_id"], name: "index_account_exports_on_user_id"
+  end
+
   create_table "account_external_id_sequences", id: :uuid, force: :cascade do |t|
     t.bigint "value", default: 0, null: false
     t.index ["value"], name: "index_account_external_id_sequences_on_value", unique: true