test(qa): summary skip-exclusion + per-month override regression (B2/B5)

- tests/summarySkipOverride.test.js: verifies the Summary excludes skipped bills
  from the monthly total and applies per-month amount overrides, alongside the
  QA-B5-01 occurrence gate (guards both from regressing together)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/summarySkipOverride.test.js

@@ -0,0 +1,72 @@
+'use strict';
+
+// B2/B5: the Summary must honour per-month monthly_bill_state modifiers — skipped
+// bills excluded from the total, per-month amount overrides applied — alongside the
+// occurrence gate added for QA-B5-01. Guards against regressions in either.
+const test = require('node:test');
+const assert = require('node:assert/strict');
+const os = require('node:os');
+const path = require('node:path');
+const fs = require('node:fs');
+
+const dbPath = path.join(os.tmpdir(), `bill-tracker-summary-skip-test-${process.pid}.sqlite`);
+process.env.DB_PATH = dbPath;
+
+const { getDb, closeDb } = require('../db/database');
+
+function callSummary(userId, year, month) {
+  const router = require('../routes/summary');
+  const layer = router.stack.find(item => item.route?.path === '/' && item.route.methods.get);
+  const handler = layer.route.stack[0].handle;
+  return new Promise((resolve) => {
+    const req = { query: { year: String(year), month: String(month) }, user: { id: userId, role: 'user' } };
+    const res = {
+      statusCode: 200,
+      status(c) { this.statusCode = c; return this; },
+      json(data) { resolve({ status: this.statusCode, data }); },
+    };
+    handler(req, res);
+  });
+}
+
+test('summary honours skip (exclude) and per-month amount override', async () => {
+  const db = getDb();
+  const userId = db.prepare(
+    "INSERT INTO users (username, password_hash, role, active) VALUES ('skip-user', 'x', 'user', 1)",
+  ).run().lastInsertRowid;
+
+  const insertBill = db.prepare(`
+    INSERT INTO bills (user_id, name, due_day, billing_cycle, cycle_type, expected_amount, active)
+    VALUES (?, ?, ?, 'monthly', 'monthly', ?, 1)
+  `);
+  const a = insertBill.run(userId, 'Bill A', 5, 10000).lastInsertRowid;  // $100
+  const b = insertBill.run(userId, 'Bill B', 10, 20000).lastInsertRowid; // $200, skipped
+  const c = insertBill.run(userId, 'Bill C', 15, 30000).lastInsertRowid; // $300, overridden to $50
+
+  const setState = db.prepare(
+    'INSERT INTO monthly_bill_state (bill_id, year, month, actual_amount, is_skipped) VALUES (?, 2026, 6, ?, ?)',
+  );
+  setState.run(b, null, 1);   // skip B
+  setState.run(c, 5000, 0);   // override C → $50
+
+  const { data } = await callSummary(userId, 2026, 6);
+  const find = (id) => data.expenses.find((e) => e.bill_id === id);
+
+  assert.equal(find(a).display_amount, 100, 'Bill A shows base amount');
+  assert.equal(find(b).is_skipped, true, 'Bill B is flagged skipped');
+  assert.equal(find(c).display_amount, 50, 'Bill C shows the per-month override');
+  assert.equal(find(c).actual_amount, 50, 'Bill C override surfaced as actual_amount');
+
+  // Counted total excludes the skipped bill and uses the override: 100 + 50 = 150.
+  const countedTotal = data.expenses
+    .filter((e) => !e.is_skipped)
+    .reduce((sum, e) => sum + e.display_amount, 0);
+  assert.equal(countedTotal, 150, 'monthly obligation excludes skipped, applies override');
+});
+
+test.after(() => {
+  closeDb();
+  for (const suffix of ['', '-wal', '-shm']) {
+    try { fs.rmSync(dbPath + suffix); } catch { /* ignore */ }
+  }
+});