Environments Phase 1: stand up DEV (prod-safe)

[billmallard]

Environments Phase 1: stand up DEV (prod-safe)

Create a DEV environment for the configurator so in-flight changes are tested
without touching prod. Ends the "upload a dev schema.json onto the live
assets/editor/schema.json" anti-pattern that control-bindings Phase 1 testing
hit (there is only one slot there today).

Spec: docs/environments.md (Phase 1).

Scope

• New Worker makerplane-configurator-dev on dev.pyefis.aerocommons.org
  (custom domain on the aerocommons.org zone).
• New D1 makerplane_configurator_dev (+ run migrations against it).
• env.dev block in wrangler.jsonc (name / routes / vars / bindings) + an ENV
  var.
• Worker composes R2 prefixes from ENV: assets under assets/editor/dev/,
  configs under configs-dev/. Keep the bare assets/editor/... working as a
  prod alias during transition so nothing dark-holes.
• Dev secrets (SESSION_SECRET, GOOGLE_*, MAIL_*) via
  wrangler secret put --env dev (or a dev-only magic-link bypass -- open Q6).
• Point our testing + the bench Pi (ssh pyefis) at DEV.

Acceptance

• wrangler deploy --env dev serves the editor at dev.pyefis.aerocommons.org
  with its own accounts/designs (dev D1) and its own schema.json (dev R2 prefix).
• Uploading a dev schema to assets/editor/dev/schema.json does NOT change prod.
• Prod (pyefis.aerocommons.org) is byte-for-byte unaffected.

Part of the DEV/QA/PROD environments epic.