invoices: self-contained payout addresses

Crypto options were limited to a hard-coded asset list, with one
address per coin in a side table. A payout address now carries
everything an invoice needs: ticker, name, QR URI scheme, amount
parameter, CoinGecko id, address and an active flag. Any coin can be
added, several addresses per ticker are fine, and known tickers fill the
QR and rate fields from the built-in templates.

The new-invoice form picks a payout address. The invoice snapshots the
ticker, address, name, scheme and amount parameter, and the PDF and QR
render from that copy, so editing, retiring or deleting a payout entry
never changes an issued invoice. "Fetch live" looks up the rate by the
payout address's CoinGecko id.

Migration 012 keeps the existing rows and backfills both the payout
metadata and the snapshots on existing crypto invoices.

Assisted-by: Claude:opus-5

db/migrations/012_payout_addresses_rework.rb

@@ -0,0 +1,51 @@
+require_relative '../../lib/crypto_asset'
+
+Sequel.migration do
+  up do
+    # A payout address now carries everything an invoice needs: ticker
+    # (coin), display name, QR URI scheme + amount parameter, CoinGecko id for
+    # the live rate, the address, and an active flag. Several per ticker.
+    alter_table(:payout_addresses) do
+      drop_constraint :payout_addresses_pkey
+      add_primary_key :id
+      add_column :name, String
+      add_column :scheme, String         # e.g. litecoin; NULL = bare address
+      add_column :amount_param, String   # amount | tx_amount; NULL = none
+      add_column :coingecko, String      # NULL = rate typed by hand
+      add_column :active, TrueClass, null: false, default: true
+    end
+
+    # Invoices snapshot the payout metadata at issue (like the address), so
+    # later edits never change an issued PDF or QR.
+    alter_table(:invoices) do
+      add_column :crypto_name, String
+      add_column :crypto_scheme, String
+      add_column :crypto_amount_param, String
+    end
+
+    CryptoAsset::DEFAULTS.each do |code, a|
+      self[:payout_addresses].where(coin: code).update(name: a[:name], scheme: a[:scheme],
+                                                       amount_param: a[:amount_param], coingecko: a[:coingecko])
+      self[:invoices].where(crypto_coin: code).update(crypto_name: a[:name], crypto_scheme: a[:scheme],
+                                                      crypto_amount_param: a[:amount_param])
+    end
+    self[:payout_addresses].where(name: nil).update(name: :coin)
+  end
+
+  down do
+    alter_table(:invoices) do
+      drop_column :crypto_amount_param
+      drop_column :crypto_scheme
+      drop_column :crypto_name
+    end
+    alter_table(:payout_addresses) do
+      drop_column :active
+      drop_column :coingecko
+      drop_column :amount_param
+      drop_column :scheme
+      drop_column :name
+      drop_column :id
+      add_primary_key [:coin]
+    end
+  end
+end