computer: Fix issues found by a deployed test of the stack

[mattzcarey]

Stacked on #189.

These fixes come from running the stack on a deployed Worker and trying to break it. The lab Durable Object had a JavaScript backend with ws:container, ws:git, a host module, and a source module, plus WorkerShellBackend and ContainerBackend, driven through createAITools both locally and through getWorkspace(stub). Each fix is its own commit.

Remote clients offered a publish that failed. A remote client's assets getter returned the stub's property, which over RPC is always a placeholder. createAITools built from getWorkspace(stub) therefore offered publish on a Workspace with no assets, and calling it failed with "The RPC receiver does not implement the method assets". The stub now exposes a plain hasAssets boolean, read once when the client is created, as useThink already is.

A result with an undefined field failed the run.

export default () => ({ kept: 1, dropped: undefined });
// before: failed, "Workspace code inputs and results must be JSON-compatible values."
// after:  completed, { kept: 1 }

The result is framed as JSON, which drops the field anyway. Values like this are common in ordinary code, so the check now treats an undefined field as absent.

A cyclic argument overflowed the stack. The isolate's early size check (#183) walked arguments without tracking what it had seen. It now stops at a repeated object and reports "must be acyclic", the same wording the host uses.

ws:container dropped the sync result. exec now also returns sync:

const { exitCode, stdout, sync } = await exec("npm install");
// sync: { status: "complete" | "pending", skipped: string[], skippedCount: number, error?: string }

pending means the container's file changes have not reached the Workspace yet, and skipped lists paths the Workspace refused, such as files in a read-only mount. The list is capped at 100 with skippedCount giving the full count, and the error is cut to 1 KiB, so a large skip can't push the result past the bridge's limits after the command has run. The lab showed one more case the report cannot catch. A file the isolate writes while the command runs is replaced by the container's version, without being reported as skipped. The module's description and docs/17_isolate_javascript.md now say the sync is last-writer-wins.

ws:git's description didn't mention -C, although cli accepts a leading -C <path>.

Script runner tests check the cyclic-argument error and the dropped undefined field in a real Dynamic Worker, and both fail without their fixes. client.test.ts checks that local and remote clients without assets leave publish out. The container module tests cover a pending sync with skipped paths.

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🦋 Changeset detected

Latest commit: ba0b9d8

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 4 packages

Name	Type
@cloudflare/computer	Patch
@cloudflare/dofs	Patch
@cloudflare/computer-rpc	Patch
@cloudflare/computerd	Patch

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commit: ba0b9d8