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/shared/managed-agents-core.md

@@ -62,6 +62,16 @@ rescheduling → running ↔ idle → terminated
 | Archive | Session becomes **read-only**. Not reversible. |
 | Delete | Permanently deletes session, event history, container, and checkpoints. |
 
+These are ops/inspection calls — typically made from a terminal, not application code. From the shell (see `shared/anthropic-cli.md`):
+
+```sh
+ant beta:sessions list --transform '{id,title,status,created_at}' --format jsonl
+ant beta:sessions retrieve --session-id "$SID"
+ant beta:sessions:events stream --session-id "$SID"   # watch events live
+ant beta:sessions archive  --session-id "$SID"
+ant beta:sessions delete   --session-id "$SID"
+```
+
 ---
 
 ## Sessions
@@ -112,6 +122,8 @@ const session = await client.beta.sessions.create(
 );
 ```
 
+> 💡 **Watch it live in Console.** While developing, print a link so you can click through to the session UI instead of parsing the event stream: `https://platform.claude.com/workspaces/{workspace}/sessions/{session.id}`. Use `default` for the workspace slug unless you created the session in a non-default workspace; the sessions list for your workspace is at `https://platform.claude.com/workspaces/default/sessions`. Include this `print`/`console.log` in code you generate for users who are iterating locally.
+
 **Session creation parameters:**
 
 | Field           | Type     | Required | Description                                    |
@@ -173,6 +185,8 @@ The agent is a **persistent resource**, not a per-run parameter. The intended pa
 
 **Anti-pattern:** calling `agents.create()` at the top of every script run. This accumulates orphaned agent objects, pays create latency on every invocation, and defeats the versioning model. If you see `agents.create()` in a function that's called per-request or per-cron-tick, that's wrong — hoist it to one-time setup and persist the ID.
 
+> **Recommended — define agents and environments as YAML + apply via the `ant` CLI.** The split is **CLI for the control plane, SDK for the data plane**: agents and environments are relatively static resources you manage with `ant` (version-controlled YAML, applied from CI); sessions are dynamic and driven by your application through the SDK. See `shared/anthropic-cli.md` → *Version-controlled Managed Agents resources* for the `ant beta:agents create < agent.yaml` / `update --version N` flow. The SDK `agents.create()` call shown elsewhere in this doc is the in-code equivalent — use it when you need to provision programmatically, but prefer the YAML flow for anything a human maintains.
+
 ### Versioning
 
 Each `POST /v1/agents/{id}` (update) creates a new immutable version (numeric timestamp, e.g. `1772585501101368014`). The agent's history is append-only — you can't edit a past version.