docs: development workflow in README

Two-terminal dev loop (go run + vite proxy), the full check matrix,
and the regenerate-types rule: web/src/types/ is generated from the
Go structs and must never be edited by hand.

README.md

@@ -4,12 +4,36 @@ Self-hosted dashboard that runs an agent-based deepfake-spread model live:
 change the levers, watch the spread, and (later) search for the best
 intervention under a budget. Output is illustrative, not validated.
 
-Status: milestone 1, porting the simulation engine.
+Status: milestone 2, thin API + parity page done.
 
-Layout:
+## Layout
 
 - `internal/engine/` - the pure simulation engine (no web dependencies)
-- `cmd/spreadlab/` - the server binary (milestone 2)
+- `internal/api/` - thin JSON API over the engine
-- `web/` - Vue 3 + TypeScript frontend (milestone 2+)
+- `cmd/spreadlab/` - the server binary (`-table` prints a CLI comparison)
+- `web/` - Vue 3 + TypeScript frontend (Vite)
+- `web/src/types/` - TypeScript types GENERATED from the Go structs; never
+  edit by hand, regenerate with `go generate ./...`
+
+## Development
+
+Two terminals:
+
+```sh
+go run ./cmd/spreadlab        # API on localhost:8080
+cd web && npm run dev         # Vite dev server, proxies /api to :8080
+```
+
+Checks:
+
+```sh
+go test ./...                              # engine + API tests
+golangci-lint run ./...                    # Go linter
+go test -bench=. -benchmem ./internal/engine/   # benchmark baseline
+cd web && npm run test:unit && npm run lint && npm run type-check
+```
+
+After changing `Config`, `Result`, or the API response types, run
+`go generate ./...` and commit the regenerated files in `web/src/types/`.
 
 MIT licensed.