feat: add .openboot.yml for one-command dev setup

Author: fullstackjam

.openboot.yml

@@ -0,0 +1,18 @@
+version: "1.0"
+
+brew:
+  packages:
+    - go
+    - git
+    - gh
+    - upx
+
+init:
+  - go mod download
+  - make build
+
+verify:
+  - go version
+  - git --version
+  - gh --version
+  - ./openboot version

CONTRIBUTING.md

@@ -7,12 +7,9 @@ Contributions are welcome. @fullstackjam maintains the project and reviews all P
 ```bash
 git clone https://github.com/YOUR_USERNAME/openboot.git
 cd openboot
+openboot init        # installs Go, upx, gh, tart — then builds
 git checkout -b fix-something
 
-# Build
-go build -o openboot ./cmd/openboot
-./openboot --dry-run
-
 # Test
 make test-unit
 
@@ -21,6 +18,8 @@ git commit -m "fix: the thing"
 git push origin fix-something
 ```
 
+> Don't have OpenBoot yet? `curl -fsSL openboot.dev/install.sh | bash`
+
 Then open a PR — use the template, it's short.
 
 ## Good First Contributions
@@ -39,6 +38,12 @@ make test-integration    # Slower
 make test-all            # Everything + coverage
 ```
 
+VM-based E2E tests require [Tart](https://github.com/cirruslabs/tart) (macOS virtualization). Install it only if you need to run `make test-vm-*`:
+
+```bash
+brew install cirruslabs/cli/tart
+```
+
 ## Code Expectations
 
 - Standard Go style (`go vet` must pass)