Add budget loan tracking

server/db.js

@@ -873,6 +873,47 @@ const MIGRATIONS = [
       ALTER TABLE calendar_events ADD COLUMN attachment_data TEXT;
     `,
   },
+  {
+    version: 28,
+    description: 'Budget loans and installment payments',
+    up: `
+      CREATE TABLE IF NOT EXISTS budget_loans (
+        id                INTEGER PRIMARY KEY AUTOINCREMENT,
+        title             TEXT    NOT NULL,
+        borrower          TEXT    NOT NULL,
+        total_amount      REAL    NOT NULL CHECK(total_amount > 0),
+        installment_count INTEGER NOT NULL CHECK(installment_count > 0),
+        start_month       TEXT    NOT NULL,
+        notes             TEXT,
+        status            TEXT    NOT NULL DEFAULT 'active'
+                                  CHECK(status IN ('active', 'paid')),
+        created_by        INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+        created_at        TEXT    NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
+        updated_at        TEXT    NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now'))
+      );
+
+      CREATE TABLE IF NOT EXISTS budget_loan_payments (
+        id                 INTEGER PRIMARY KEY AUTOINCREMENT,
+        loan_id            INTEGER NOT NULL REFERENCES budget_loans(id) ON DELETE CASCADE,
+        installment_number INTEGER NOT NULL CHECK(installment_number > 0),
+        amount             REAL    NOT NULL CHECK(amount > 0),
+        paid_date          TEXT    NOT NULL,
+        budget_entry_id    INTEGER REFERENCES budget_entries(id) ON DELETE SET NULL,
+        created_by         INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+        created_at         TEXT    NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
+        UNIQUE(loan_id, installment_number)
+      );
+
+      CREATE TRIGGER IF NOT EXISTS trg_budget_loans_updated_at
+        AFTER UPDATE ON budget_loans FOR EACH ROW
+        BEGIN UPDATE budget_loans SET updated_at = strftime('%Y-%m-%dT%H:%M:%SZ', 'now') WHERE id = OLD.id; END;
+
+      CREATE INDEX IF NOT EXISTS idx_budget_loans_status ON budget_loans(status);
+      CREATE INDEX IF NOT EXISTS idx_budget_loans_start_month ON budget_loans(start_month);
+      CREATE INDEX IF NOT EXISTS idx_budget_loan_payments_loan ON budget_loan_payments(loan_id);
+      CREATE INDEX IF NOT EXISTS idx_budget_loan_payments_paid_date ON budget_loan_payments(paid_date);
+    `,
+  },
 ];
 
 /**