Refactor coaster to ride any time series, not just stocks

[Jonezzyboy]

Closes #1

The coaster engine is now data-agnostic: a ride is any time series, not just a stock chart. Existing stock rides are untouched (regenerated index.json came out byte-identical for all 14).

How it works

New src/series.js normalization layer. Every ride JSON — legacy stock format or the new generic format — passes through normalizeRide() at load, producing the one shape the engine consumes:

• points[].value (from value, or legacy close)
• norm(v) → 0..1 altitude scale: log or linear, explicit via "scale" or auto-detected (log when all values are positive and the range spans ≥4x)
• fmtValue() display formatting: currency for stocks, unit: { prefix, suffix } otherwise (with K/M/B abbreviation)
• stats computed generically, with zero/negative values guarded throughout
• headlines/milestones attach to the nearest point by date in the engine, so raw series need no preprocessing

Engine decoupling. Track altitude uses ride.norm/spanScore instead of hardcoded Math.log(close); HUD, minimap, menu previews, and the ride-end summary use fmtValue/norm, tolerate series without dates (point labels instead of year markers), and switch wording for non-currency rides (TOTAL CHANGE/WORST DIP vs TOTAL RETURN/$1,000 INVESTED); terrain seeding and signage key off ride.id. Drawdown embers, ATH confetti, and the lava trench all still fire — they were already value-relative.

Feeding in a series

1. ?data=<url> fetches any series JSON and boards it directly (e.g. ?data=data/TOKENS.json&go=1)
2. Drop a JSON in data-pipeline/series/ and run npm run data:series — published to public/data/ and added to the menu; the pipeline now regenerates index.json from output files

Format documented in the README ("Ride any time series").

Demo ride: TOKENS

A startup's daily Claude token usage over a year (373 points, ~1.5M → ~128M tok/day): agent-mode liftoff, an HN spike, a 95% region outage that carves the lava trench and fires a "REGION OUTAGE" billboard, and a prompt-caching dip. Rides as a NIGHTMARE-rated coaster with the HUD reading "118.4M tok, +8149% since start".

Testing

• test/smoke.mjs grows a leg riding TOKENS via ?data= (checks the unit renders and the cart advances); full suite passes with 15 menu cards and zero console errors
• Screenshot-verified: menu card, outage/trench section, peak gold blocks, and both generic and stock end-summaries
• Bonus fix along the way: the intraday SPCX summary now reads "DAYS RIDDEN 1" instead of "YEARS RIDDEN 0.0"

🤖 Generated with Claude Code