Add examples/ folder with runnable usage scripts

[pimfeltkamp]

Summary

Adds five self-contained TypeScript examples for the most common usage patterns. Each script is one file, reads its bearer token from CRYPTOHOPPER_TOKEN, and runs with npx tsx <file>.ts.

File	What it shows
public-ticker.ts	Public endpoint, no token, single ticker fetch
whoami.ts	Minimal authenticated request
list-hoppers.ts	List resource with optional filter
error-handling.ts	CryptohopperError codes / status / retryAfterMs / serverCode
start-backtest.ts	Long-running async resource — submit, poll, render result

Why

Currently a new user lands on the README, gets a Quickstart snippet, and has no working file they can git clone && cd && npx tsx into. Every adjacent SDK ecosystem (Stripe, Twilio, Supabase) ships an examples/ folder for exactly this reason. This is the missing on-ramp.

Layout

• examples/package.json is a separate workspace pinning @cryptohopper/sdk + tsx + typescript@6 + @types/node@25. It does not affect the SDK's published surface.
• examples/tsconfig.json typechecks the scripts in strict mode against the built dist/ typings. Verified clean (tsc --noEmit exit 0).
• examples/.gitignore keeps node_modules/ and a per-folder package-lock.json out of git.

Test plan

• tsc --noEmit exits 0 for every example
• node --experimental-strip-types --check passes on every example
• (manual) CRYPTOHOPPER_TOKEN=… npx tsx whoami.ts runs end-to-end against prod
• (manual) npx tsx public-ticker.ts works without any token

[pimfeltkamp]

Pushed a follow-up commit renaming public-ticker.ts to ticker.ts. The original example called new CryptohopperClient({ apiKey: "" }) — that throws a TypeError because the SDK validates apiKey at construction, and the API gateway has no anonymous routes anyway. The renamed version reads CRYPTOHOPPER_TOKEN like every other example. Same false-claim cleanup that landed in resources#9. Diff is 1 file added, 1 deleted, 3-line README touch-up. No re-review needed beyond confirming the rename.