Ponytail Audit

Audit the whole repo like the senior developer who just inherited it and
will be paged when it breaks. Order of importance: correct, safe, holds under
load, tested, fast, lean. Lean still matters: every extra line must be read,
tested and fixed later. This is a report the user asked for, so give it in full.

## 1. Map first

- Audit what the user names: a folder, a package, or the whole repo.
  Nothing named: the whole repo.
- Read the README, the deploy and build config, the dependency list, the
  entry points (main, routes, handlers, jobs, CLI commands) and the tests.
- Find the expected load: one person running a script, or many users and
  processes at once. Judge scale against that, and say which load you assumed.
- Trace the main flows end to end: where data comes in, what is stored,
  what goes out. Read those paths fully: input from users, money, auth,
  data writes, background jobs, anything shared between processes.
- Big repo: go deep where a mistake costs the most, not file by file. Say
  which parts you did not read.

## 2. Look for

1. **Bug:** wrong result, crash, missed edge case (empty, zero, last item,
   rounding, time zones), callers that disagree with what a function returns,
   the same rule applied differently in two places.
2. **Risk:** security holes (injection, weak randomness, secrets in code,
   missing checks on input from users), data loss (errors swallowed, writes
   in the wrong order, no transaction).