This reverts:
- 28b03595b research: delete Hono backend (do not merge) (#25667)
- b24a4e897 chore(server): clean up post-Hono-deletion scar tissue (#26542)
v1.14.42 broke startup for users with plugins that depend on the
Hono wire format (most visibly opencode-gemini-auth, see #26546).
Restoring Hono as the default backend on stable channels while we
investigate the actual plugin compatibility story.
OPENCODE_EXPERIMENTAL_HTTPAPI flag and dual-backend selection come
back. Stable installs default to Hono; dev/beta default to HTTP API.
Conflict resolution: took the pre-deletion side for control-plane
schemas and the seven test files where post-deletion follow-up PRs
had also touched the conflicting lines. The HTTP API code added
since the deletion (compression, cors-vary, fence, lifecycle log,
account error mapping, etc.) is preserved as-is — those still apply
on the HTTP API path for users on dev/beta channels.
