Initial commit on Forgejo

Fresh repository history for elektrine/tarakan hosted at
https://git.elektrine.com/elektrine/tarakan.

priv/repo/migrations/20260724081002_create_credit_ledger.exs

@@ -0,0 +1,30 @@
+defmodule Tarakan.Repo.Migrations.CreateCreditLedger do
+  use Ecto.Migration
+
+  def change do
+    create table(:credit_entries) do
+      add :account_id, references(:accounts), null: false
+      add :amount, :integer, null: false
+      add :kind, :string, null: false
+      add :subject_type, :string
+      add :subject_id, :bigint
+      add :balance_after, :integer, null: false
+
+      timestamps(type: :utc_datetime_usec, updated_at: false)
+    end
+
+    create index(:credit_entries, [:account_id, :id])
+
+    # Mint idempotency: one entry per (kind, subject, account). Postgres treats
+    # NULLs as distinct, and non-mint entries have no subject, so the index is
+    # partial on rows that carry a subject.
+    create unique_index(:credit_entries, [:kind, :subject_type, :subject_id, :account_id],
+             name: :credit_entries_mint_unique_index,
+             where: "subject_type IS NOT NULL"
+           )
+
+    alter table(:accounts) do
+      add :credit_balance, :integer, null: false, default: 0
+    end
+  end
+end