feat(spec)!: reset Application contract to v1alpha1 (#203)

* feat(spec)!: reset Application contract to v1alpha1

Adopt the Kubernetes-shaped onebox.run/v1alpha1 resource, publish and embed its schema, migrate all fixtures and docs, and remove the v1 compatibility surface.

BREAKING CHANGE: onebox.run/v1, snake_case declarative fields, lowercase enum values, root workload shorthand, aliases, and fallbacks are no longer accepted.

* fix(spec): enforce v1alpha1 contract edges

* docs: update remaining v1alpha1 schema links

Author: vishr

README.md

@@ -75,15 +75,20 @@ Starting from an existing Compose project, `ob init` writes the first draft.
 This is a complete single-workload project:
 
 ```yaml
-# yaml-language-server: $schema=https://raw.githubusercontent.com/labstack/onebox/main/docs/onebox.run-v1.schema.json
-api_version: onebox.run/v1
-app: shop
-environments:
-  production:
-    server: root@203.0.113.10
-image: ghcr.io/acme/shop:1.4.0
-routes:
-  - {hostname: shop.example.com, port: 3000}
+# yaml-language-server: $schema=https://onebox.run/schemas/application/v1alpha1/application.schema.json
+apiVersion: onebox.run/v1alpha1
+kind: Application
+metadata:
+  name: shop
+spec:
+  environments:
+    production:
+      server: root@203.0.113.10
+  workloads:
+    web:
+      image: ghcr.io/acme/shop:1.4.0
+      routes:
+        - {hostname: shop.example.com, port: 3000}
 ```
 
 It derives the application container, Traefik routing and TLS, release layout