docs: add from-scratch bootstrap steps for agent

- Prerequisites check
- Clone + checkout instructions
- Build and smoke test commands
- Development loop (edit → build → vet → test)
- Git user config with sign-off

Signed-off-by: Boos4721 <boos4721@icloud.com>

plan/go-backend-rewrite.md

@@ -2,11 +2,85 @@
 
 You are a senior Go developer tasked with rewriting the BoosAPI backend from Node.js/Fastify/TypeScript to Go. The frontend (React SPA) and database schema remain unchanged.
 
+## Getting Started (from scratch)
+
+### Prerequisites
+
+The agent must have these tools available:
+- `git` — clone and push code
+- `go` (1.26+) — build and test
+- `gofmt` — code formatting (comes with Go)
+- `curl` — API testing
+- `docker` (optional) — container build
+
+### Step-by-step bootstrap
+
+```bash
+# 1. Clone the repository
+git clone https://git.boos.lat/boos/BoosAPI.git boosapi-go
+cd boosapi-go
+
+# 2. Checkout the rewrite branch
+git checkout refactor/go-backend
+
+# 3. Verify Go version
+go version  # must be 1.26+, install if missing
+
+# 4. Build Phase 1 scaffold
+CGO_ENABLED=0 go build ./cmd/boosapi/
+
+# 5. Quick smoke test
+AUTH_TOKEN=admin PROXY_TOKEN=proxy ./boosapi &
+sleep 2
+curl -s http://localhost:4000/healthz
+# Expected: {"status":"ok","database":"ok",...}
+kill %1
+
+# 6. Run existing tests
+go test ./... -count=1
+go vet ./...
+
+# 7. Verify Phase 1 is complete
+ls cmd/boosapi/main.go
+ls internal/config/config.go
+ls internal/db/db.go
+ls internal/server/middleware/middleware.go
+ls internal/server/handler/health.go
+ls internal/db/migrate/000001_initial.up.sql
+ls docker/Dockerfile
+# All should exist
+```
+
+### Development loop
+
+```bash
+# Edit code, then:
+CGO_ENABLED=0 go build ./cmd/boosapi/  # compile check
+go vet ./...                            # static analysis
+go test ./... -count=1 -v              # run tests (add -run TestName for specific)
+AUTH_TOKEN=admin PROXY_TOKEN=proxy ./boosapi &  # manual test
+curl http://localhost:4000/healthz
+kill %1
+
+# Before commit:
+gofmt -s -w .   # format all Go files
+go vet ./...    # final vet check
+go test ./...   # final test run
+```
+
+### Git configuration
+
+```bash
+git config user.name "Boos4721"
+git config user.email "boos4721@icloud.com"
+# Always sign off commits: git commit -s
+```
+
 ## Repository
 
 - **Branch:** `refactor/go-backend`
 - **Remote:** `gitea` (`https://git.boos.lat/boos/BoosAPI.git`)
-- **Go version:** 1.26
+- **Go version:** 1.26+
 - **Module:** `github.com/cita-777/boosapi`
 
 ## Golden Rules