Add the Corporate Ladder pack, and two engine features it needed

Seventeen events across the mailroom: ordinary days, Marlene Hobb and Trevor
Pike, a misrouted envelope that can be delivered or kept, and a hard-times
branch that fires on negative money and always leaves an ungated way out.

Writing real content turned up two things the engine could not express.

Per-turn upkeep (`pack.upkeep`): the MVP spec wants recurring income and costs,
but effects only run when a player chooses something, and baking wages into
every option would be tedious and easy to get wrong. Upkeep entries carry their
own conditions, which turned out to be enough for the loan service charge to be
a three-step function that escalates with the size of the debt — no multiply
operation, no engine change. Upkeep changes are recorded separately from choice
changes so the UI can distinguish them.

Per-character starting relationships: Trevor starts below the pack default on
`likes_you` because he arrived two weeks earlier and has priced that in.
Characterisation as data rather than as an opening cutscene. Nobody starts
feared, either — `fears_you` defaults to 10, since a midpoint default would mean
every new hire arrives already intimidating.

The content suite plays 60 seeded runs and asserts every event fires and every
option is taken at least once. That caught real dead content: Trevor's favour
chain sat behind a gate no plausible player could reach, taking two events and a
hard-times escape route with it, and debt could pass 5,500 while the service
charge stayed flat, so the failure spiral flattened out instead of tightening.
Both fixed in the data — the gate softened and given another route up, the loan
capped and its charge tiered.

The validator also gained a real fix: it counted an event with a cooldown as a
stage's fallback, but a cooldown can exclude it, so a stage could still run dry.

86 tests. Reasoning in docs/DECISIONS.md §11-13, including the seeding trap that
makes a correlated chooser look exactly like a content bug.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VMSFHyVPitUoosW5wyEADj

content/corporateladder/index.js

@@ -0,0 +1,76 @@
+// Corporate Ladder — the default content pack for The Ladder.
+//
+// A modern office, the mailroom, and two people who have been there longer
+// than you. Everything the engine needs to run this setting is in this file
+// and the ones it imports; the engine itself knows nothing about mailrooms.
+
+import { characters } from './characters.js';
+import { events } from './events/index.js';
+
+export const corporateLadder = {
+  id: 'corporateladder',
+  name: 'Corporate Ladder',
+  version: '0.1.0',
+  turnUnit: 'day',
+  startingStage: 'mailroom',
+
+  stages: {
+    mailroom: { label: 'Mailroom', title: 'Mail Associate I' },
+  },
+
+  // Money is deliberately tight: the baseline is a slow bleed (see `upkeep`),
+  // so the pressure that eventually forces a hard-times turn comes from doing
+  // nothing about it, and most of the ways out cost standing rather than cash.
+  state: {
+    'money': { initial: 400, min: -5000, max: 1000000 },
+    'debt': { initial: 0, min: 0, max: 1000000 },
+    'reputation': { initial: 50, min: 0, max: 100 },
+    'skills.negotiation': { initial: 5, min: 0, max: 100 },
+    'skills.logistics': { initial: 5, min: 0, max: 100 },
+    'flags.took_loan': { initial: false },
+    'flags.holds_the_envelope': { initial: false },
+    'flags.covered_for_trevor': { initial: false },
+    // Moments the retrospective reads back. Content decides what is memorable;
+    // the full turn-by-turn record lives in history regardless.
+    'notable': { initial: [] },
+  },
+
+  // Nobody fears a new hire. Trevor's defaults are lower still — see
+  // characters.js, where he starts two weeks ahead of you and knows it.
+  relationshipStats: {
+    likes_you: { initial: 50, min: 0, max: 100 },
+    fears_you: { initial: 10, min: 0, max: 100 },
+    wants_to_help_you: { initial: 40, min: 0, max: 100 },
+  },
+
+  // Applied at the end of every turn, after the player's choice. Net -25 a day
+  // before anything else happens, so a run drifts toward trouble in about
+  // sixteen days if it is left alone.
+  upkeep: [
+    { label: 'Wages', effects: [{ path: 'money', op: 'add', value: 115 }] },
+    { label: 'Living costs', effects: [{ path: 'money', op: 'add', value: -140 }] },
+    // The service charge steps up with the size of the debt, so the spiral
+    // tightens instead of flattening out. A step function in data costs the
+    // engine nothing; a percentage would have needed a multiply operation.
+    {
+      label: 'Loan service charge',
+      requires: [{ path: 'debt', op: '>', value: 0 }],
+      effects: [{ path: 'money', op: 'add', value: -10 }],
+    },
+    {
+      label: 'Loan service charge (arrears)',
+      requires: [{ path: 'debt', op: '>=', value: 1000 }],
+      effects: [{ path: 'money', op: 'add', value: -15 }],
+    },
+    {
+      label: 'Loan service charge (collections)',
+      requires: [{ path: 'debt', op: '>=', value: 2000 }],
+      effects: [{ path: 'money', op: 'add', value: -25 }],
+    },
+  ],
+
+  characters,
+  events,
+};
+
+export default corporateLadder;