chore: update claude-api skill (#956)

Add shared/model-migration.md and refresh model references, managed
agents docs, and skill description across all language guides.

skills/claude-api/ruby/claude-api.md

@@ -26,7 +26,7 @@ client = Anthropic::Client.new(api_key: "your-api-key")
 
 ```ruby
 message = client.messages.create(
-  model: :"claude-opus-4-6",
+  model: :"claude-opus-4-7",
   max_tokens: 16000,
   messages: [
     { role: "user", content: "What is the capital of France?" }
@@ -46,7 +46,7 @@ end
 
 ```ruby
 stream = client.messages.stream(
-  model: :"claude-opus-4-6",
+  model: :"claude-opus-4-7",
   max_tokens: 64000,
   messages: [{ role: "user", content: "Write a haiku" }]
 )
@@ -78,7 +78,7 @@ class GetWeather < Anthropic::BaseTool
 end
 
 client.beta.messages.tool_runner(
-  model: :"claude-opus-4-6",
+  model: :"claude-opus-4-7",
   max_tokens: 16000,
   tools: [GetWeather.new],
   messages: [{ role: "user", content: "What's the weather in San Francisco?" }]
@@ -99,7 +99,7 @@ See the [shared tool use concepts](../shared/tool-use-concepts.md) for the tool
 
 ```ruby
 message = client.messages.create(
-  model: :"claude-opus-4-6",
+  model: :"claude-opus-4-7",
   max_tokens: 16000,
   system_: [
     { type: "text", text: long_system_prompt, cache_control: { type: "ephemeral" } }

skills/claude-api/ruby/managed-agents/README.md

@@ -51,7 +51,7 @@ puts "Environment ID: #{environment.id}" # env_...
 # 1. Create the agent (reusable, versioned)
 agent = client.beta.agents.create(
   name: "Coding Assistant",
-  model: :"claude-opus-4-6",
+  model: :"claude-opus-4-7",
   system_: "You are a helpful coding assistant.",
   tools: [{type: "agent_toolset_20260401"}]
 )
@@ -260,7 +260,7 @@ client.beta.sessions.delete(session.id)
 # Agent declares MCP server (no auth here — auth goes in a vault)
 agent = client.beta.agents.create(
   name: "GitHub Assistant",
-  model: :"claude-opus-4-6",
+  model: :"claude-opus-4-7",
   mcp_servers: [
     {
       type: "url",