Create the modular server/ layout from PHASE-1-sidecar.md §Architecture Sketch:
server/types.ts — shared WsClient/WsServer/RemoteServer interfaces
server/upgrade.ts — WS upgrade routing per path (LEGACY /ws)
server/server.ts — HTTP bootstrap, middleware, LEGACY HTML routes
server/routes/ — empty dir, placeholder for T-1.5/T-1.6/T-1.7
The original extensions/remote-control/server.ts is replaced with a
thin re-export shim so that index.ts continues to resolve
'./server.js' without changes.
All LEGACY code paths (manifest.json, icon.svg, /, /ws) are tagged
with // LEGACY: … comments. No behaviour changes. No new endpoints.
Pre-existing biome errors in auth.ts, config.ts, index.ts are
unchanged — NOT introduced by this commit.
jay