[Core] Add Factory Pause Checkpoints

[MRayermannMSFT]

What

Adds token-scoped factory pause and durable checkpoint APIs to the Node.js SDK after the runtime contract lands. A paused attempt settles its waiter while resume preserves invocation limit overrides and execution identity.

Why

Factory authors need a safe checkpoint that stops spend without losing completed work. Token-scoped aborts stop an old attempt from cancelling a resumed attempt with the same run ID.

[github-actions]

SDK Consistency Review

Scope of PR #2537: Adds pause support (a ctx.pause(key) durable checkpoint, session.factory.pause(runId), and a paused terminal-ish run status) plus a rename of FactoryLimits → FactoryLimitOverrides, exclusively in the Node.js/TypeScript SDK (nodejs/src/factory.ts, nodejs/src/session.ts, nodejs/src/index.ts, generated RPC types, and tests).

Cross-SDK check: The Agent Factories feature (session.factory.*, defineFactory, FactoryContext, etc.) currently only has a full client-side implementation in the Node.js SDK. Python, Go, .NET, and Rust have no factory-related source files at all. Java only contains generated RPC schema types under java/sdk/src/generated/java/.../rpc/ (e.g., FactoryRunResult, FactoryDeclaredLimits) — there is no hand-written SessionFactoryApi-equivalent client surface in Java's main/java source, and it does not yet expose an equivalent to pause/FactoryContext.pause.

Conclusion: This PR extends an already Node.js-only (experimental) feature area rather than introducing a new cross-language asymmetry — the other SDKs (Python, Go, .NET, Rust, and Java's hand-written client) did not have factory pause/limits parity before this PR, and still don't, but that gap pre-dates this change. No inline consistency issues to flag for this PR specifically.

Suggestion (non-blocking): Since Agent Factories is marked @experimental and evolving quickly (this PR alone adds pause, changes abort to be per-execution-token, and renames FactoryLimits), it may be worth tracking a follow-up item for bringing Java (and eventually other SDKs) up to parity with the Node.js factory client surface before the feature graduates out of experimental status.

Generated by SDK Consistency Review Agent for #2537 · copilot · sonnet50 · 27.6 AIC · ⌖ 12 AIC · ⊞ 9.7K · ◷