devvit: decide classic public-api vs Devvit Web (research doc contradicts shipped code)

[bakerboy448]

Problem

devvit-migration/docs/03-research-platform.md:11 states:

The classic Devvit.addSchedulerJob / Devvit.addSettings / Devvit.addTrigger builder API (from version-0.11 docs) is the old model. Target the Devvit Web model.

The scaffold landed in PR #34 is built entirely on the deprecated classic model instead:

• devvit/package.json:19 — "@devvit/public-api": "0.13.5"
• devvit/src/main.ts:32,64-67,123,157,174 — Devvit.configure, Devvit.addSchedulerJob, Devvit.addTrigger

This is a direct contradiction between the platform research doc and the shipped code, not a documented tradeoff.

Decision needed

Pick one, deliberately, and document it in devvit-migration/docs/STATUS.md:

1. Stay on the classic @devvit/public-api builder model (update 03-research-platform.md to reflect that this is intentional, e.g. because Devvit Web wasn't GA when scaffolding started, or because classic has lower migration risk).
2. Port to the Devvit Web model (@devvit/web/server, @devvit/redis, @devvit/web/shared, @devvit/reddit, devvit.json-declared capabilities) as the research doc recommends.

This decision changes the import surface for every module, so it should land before further build work (FR-7/FR-8, playtest) to avoid a second rewrite.

References

PR #34 (feat/devvit-migration), devvit-migration/docs/STATUS.md §7a.