feat(providers): add createos sandbox provider

[pratikbin]

What

Adds a SandboxProvider for the createos (@nodeops-createos/sandbox) VM sandbox control plane, so sandbox-agent can provision and drive coding agents on createos sandboxes — the same way it already supports e2b, daytona, modal, vercel, cloudflare, etc.

Modeled on the existing e2b provider (closest analogue: remote API sandbox → curl-install sandbox-agent → start server → expose via host URL).

Changes

File	Change
sdks/typescript/src/providers/createos.ts	New. createos(opts) factory returning SandboxProvider.
sdks/typescript/package.json	./createos subpath export + optional peerDep/devDep @nodeops-createos/sandbox.
sdks/typescript/tsup.config.ts	New build entry + external.
sdks/typescript/tests/createos.test.ts	New. Unit test: real SDK driven through a mocked fetch.
sdks/typescript/tests/providers.test.ts	Registry entry, gated on CREATEOS_API_KEY.
examples/createos/	New. Runnable example mirroring examples/e2b.

Provider behavior

• create() — provisions a sandbox with ingress_enabled: true, then runs (each via bash -lc, PATH-exported): curl …/install.sh, sandbox-agent install-agent {claude,codex}, sandbox-agent server --port 3000.
• getUrl() — returns the ingress preview URL for the agent port; enables ingress first if it was off.
• pause / kill / destroy / reconnect / ensureServer — mapped onto the SDK lifecycle. reconnect resumes paused sandboxes and maps CreateosSandboxNotFoundError → SandboxDestroyedError. ensureServer is idempotent (duplicate server exits on port conflict).
• Defaults: shape s-1vcpu-1gb (createos requires a shape — override via shape/create), cwd /root, agent port 3000, https ingress scheme.

Testing

Unit (tests/createos.test.ts) — drives the real @nodeops-createos/sandbox SDK through a mocked fetch (its documented test seam). 6/6 pass. Asserts: create issues the right install/server command strings with ingress enabled; getUrl builds the ingress URL and PATCHes setIngress when off; destroy/pause hit the right endpoints; ensureServer restarts the server.

Live — verified end-to-end against the production control plane (api.sb.createos.sh):

```
/v1/health -> 200 {"status":"ok"}
session model=haiku # "Set model to haiku (claude-haiku-4-5-20251001)"
prompt done: {"stopReason":"end_turn", ...}
```

Provision → install agent → ingress reachable → Claude Code session on haiku → prompt round-trip → teardown, all green.

Gates: SDK build ✅ · typecheck ✅ · biome ✅ · example typecheck ✅.

Notes for reviewer

• pnpm-lock.yaml intentionally omitted. Adding the dep regenerates 1400+ lines of unrelated transitive bumps (preexisting drift between the committed lock and the registry). Run `pnpm install` to refresh the lock.
• baseUrl required on @nodeops-createos/sandbox@0.6.0. The production default (https://api.sb.createos.sh) is a newer unreleased SDK commit; on 0.6.0, pass client.baseUrl or set CREATEOS_SANDBOX_BASE_URL. The example/test do this.