Update claude-api skill: auth, cloud providers, Managed Agents fixes, token counting (#1276)

* Sync claude-api skill with latest upstream updates

- Add token-counting.md and SKILL.md trigger description update
- Add auth guidance: env credential resolution, ant auth login, OAuth/WIF doc links, 401 causes
- Add mid-conversation system messages (beta) to prompt-caching, agent-design, SKILL.md, Python/TS READMEs
- Add cache pre-warming (max_tokens: 0) section to prompt-caching
- Add Managed Agents pre-flight viability check to onboarding and overview
- Add Bedrock model-ID section to model-migration; add Bedrock row to live-sources
- Add /claude-api migrate subcommand row and migrate-entry callout
- Fix MA networking config: limited type with allow_package_managers/allow_mcp_servers
- Bump MA create-operations rate limit to 300 RPM
- Fix MA SDK drift: sessions.events.stream(), event.name, typed event arrays
- Add SDK coverage: stop_details, error .type, C# tool runner + MA support, Go model constants, Java 2.34.0, client config, response helpers, auto-pagination, advisor tool
- Move Sonnet 4 / Opus 4 to deprecated in models.md

* Add Anthropic CLI and Claude Platform on AWS docs to claude-api skill

- Add shared/anthropic-cli.md: install, auth profiles, OAuth scopes, command
  structure, version-controlled Managed Agents resources, credential traps
- Add shared/claude-platform-on-aws.md: AnthropicAWS clients, SigV4 auth,
  workspace_id, regions, feature availability
- Restore cross-references to both files throughout SKILL.md and the
  managed-agents docs (previously rewritten to live-sources.md pointers)
- Restore Claude Platform on AWS provider taxonomy in SKILL.md, the
  migration-guide section, and live-sources rows

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

@@ -15,10 +15,12 @@ pip install anthropic
 ```python
 import anthropic
 
-# Default (uses ANTHROPIC_API_KEY env var)
+# Default — resolves credentials from the environment:
+# ANTHROPIC_API_KEY, or ANTHROPIC_AUTH_TOKEN, or an `ant auth login` profile.
+# Prefer this for local dev; don't hardcode a key.
 client = anthropic.Anthropic()
 
-# Explicit API key
+# Explicit API key (only when you must inject a specific key)
 client = anthropic.Anthropic(api_key="your-api-key")
 ```
 
@@ -129,7 +131,7 @@ client.beta.sessions.events.send(
 import json
 
 # Stream-first: open stream, then send while stream is live
-with client.beta.sessions.stream(
+with client.beta.sessions.events.stream(
     session_id=session.id,
 ) as stream:
     client.beta.sessions.events.send(
@@ -140,7 +142,7 @@ with client.beta.sessions.stream(
         ...  # process events
 
 # Standalone stream iteration:
-with client.beta.sessions.stream(
+with client.beta.sessions.events.stream(
     session_id=session.id,
 ) as stream:
     for event in stream:
@@ -150,7 +152,7 @@ with client.beta.sessions.stream(
                     print(block.text, end="", flush=True)
         elif event.type == "agent.custom_tool_use":
             # Custom tool invocation — session is now idle
-            print(f"\nCustom tool call: {event.tool_name}")
+            print(f"\nCustom tool call: {event.name}")
             print(f"Input: {json.dumps(event.input)}")
             # Send result back (see below)
         elif event.type == "session.status_idle":
@@ -210,7 +212,7 @@ def run_custom_tool(tool_name: str, tool_input: dict) -> str:
 def run_session(client, session_id: str):
     """Stream events and handle custom tool calls."""
     while True:
-        with client.beta.sessions.stream(
+        with client.beta.sessions.events.stream(
             session_id=session_id,
         ) as stream:
             tool_calls = []
@@ -232,7 +234,7 @@ def run_session(client, session_id: str):
         # Process custom tool calls
         results = []
         for call in tool_calls:
-            result = run_custom_tool(call.tool_name, call.input)
+            result = run_custom_tool(call.name, call.input)
             results.append({
                 "type": "user.custom_tool_result",
                 "custom_tool_use_id": call.id,