fix(sandbox-adapter): stop Pi env calls when the run aborts

[eersnington]

Pi passes the run's Context to every env call, and context.abortSignal fires when the run stops (an abort action, a destroy, or the end of the sleep grace period). Only exec read it. A Stop during a sandbox cold start still wrote the file once the sandbox came up, and Pi's abort waited for it.

sequenceDiagram
    participant Client
    participant Pi as Pi Durable
    participant Env as sandboxEnv
    participant Sandbox
    Pi->>Env: writeFile("hello.txt", context)
    Env->>Sandbox: connect() (cold start)
    Client->>Pi: conversation.abort()
    Pi-->>Env: context.abortSignal fires
    Sandbox-->>Env: connected
    Note over Env: before: writes hello.txt<br/>after: returns FileError("aborted")

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Sandbox env (sandbox-env.ts):

-const withSandbox = async (fail, use) => {
+const withSandbox = async (context, fail, use) => {
+	if (context.abortSignal?.aborted) return err(fail(new Error("aborted")));
 	let sandbox;
 	try { sandbox = await connect(); } catch (error) { return err(fail(toError(error))); }
+	if (context.abortSignal?.aborted) return err(fail(new Error("aborted")));
 	return use(sandbox);
 };

• The connect itself keeps going. It is shared by every call of the Actor generation, so other calls can still use it.
• A failure while the signal is aborted gets the code aborted, as exec already did.

Database env (database-env.ts):

• Each operation and each reader call checks the signal before its query.
• scanLines checks it before each 64 KiB chunk, so a scan of a large file stops early.

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This is part 2 of 9 in a stack:

•  9  docs(agents): type the React example's root id as ConversationId #346
•  8  feat(pi): prefix Pi Durable's tables in actor sqlite #345
•  7  chore(pi): bump and test Pi Durable 1.1.0 #344
•  6  refactor(pi): type action ids with Pi's branded id types #343
•  5  refactor(sandbox-adapter): simplify sandboxEnv #342
•  4  refactor(pi): move databaseEnv into pi and version pi_file #341
•  3  fix(sandbox-adapter): stop waiting on aborted Daytona exec #340
•  2  fix(sandbox-adapter): stop Pi env calls when the run aborts #339 👈
•  1  fix(pi): read an app credential with one source call #338