Epic: DEV/QA/PROD environments (configurator + editor assets + branches)

[billmallard]

Tracking issue for the DEV / QA / PROD environment structure across the
configurator, editor assets, and branch layout.

Spec: docs/environments.md

Why

One environment today (prod): one Worker, one D1, one R2 bucket, one domain. The
pyEfis-generated schema.json / palette SVGs / groups.json are uploaded
straight to prod by hand, so testing an in-flight change means touching prod.
Control-bindings Phase 1 testing just uploaded a display-changes schema onto the
live assets/editor/schema.json -- the only slot there is. Three isolated
environments turn "can't test until merge" into "test on DEV, promote to PROD."

Work items

• Phase 1 -- stand up DEV (prod-safe): Environments Phase 1: stand up DEV (prod-safe) #21
• Phase 2 -- QA env + branch lines (develop/qa/main across pyEfis, makerplane-data, fix-gateway)
• Phase 3 -- CI: generate + upload assets and deploy the Worker per branch; promotion action (develop -> qa -> main)
• Phase 4 -- finish isolation: env-scoped config storage + device env pairing; drop the prod alias

Open questions (spec section 9)

Branch names; D1-per-env vs shared env column; dev/qa subdomains + certs;
config storage prefix vs bucket; dev auth (separate OAuth vs magic-link bypass).
Nav-data pipeline (navdata.aerocommons.org) is OUT of scope -- its own prod
system.