fix(cli): bound, trace, and explain the requests the CLI makes - #6798

Four transport gaps, all of which failed silently.

A request had no timeout, so a connection that was accepted and then never
answered hung the terminal indefinitely. `SIM_TIMEOUT_SECONDS` now bounds
one, defaulting to 3600s — deliberately above every timeout the server
itself applies, since a synchronous workflow run is allowed 3000s on a paid
plan and a tighter default would abort real work and report it as a
transport failure. `0` removes the bound, for a self-hosted deployment that
runs executions without one of its own. The caller's abort signal is
composed with the timeout rather than replaced, so neither masks the other.

Node ignores HTTP(S)_PROXY unless NODE_USE_ENV_PROXY opts in, and only from
v22.21 and v24.5, so on a network that reaches the API only through a proxy
every command failed to connect while the variable that would have fixed it
was already set. The CLI cannot enable that from inside the process — Node
reads it at startup — so it says what to do rather than bundling an HTTP
stack for a setting the platform now owns.

An API key was sent to any http:// endpoint with no signal. Now a warning,
not a refusal: http is the documented way to reach a local dev server, and
a deployment terminating TLS at a gateway is real. Loopback stays silent.

`SIM_DEBUG=1` traces method, URL, status and duration. Bodies and headers
are deliberately absent — the request carries the API key, and `secrets set`
carries the secret itself.

All four write to stderr, so a piped stdout stays parseable.

Two ways the new timeout could fail before the request was made.

`AbortSignal.any` arrived in Node 20.3 and this package supports Node 20, so
composing a caller's abort signal with the timeout threw a bare TypeError on
the earliest 20.x releases. It is now used when present and composed through
an AbortController when not.

`AbortSignal.timeout` rejects a fractional millisecond outright, and past
2^31-1 ms it does not fail at all — it clamps to 1ms, so the longest timeout
anyone asked for became the shortest. The value is now rounded and refused
above what Node can actually wait, pointing at 0 for an unbounded wait.

Also unstubs env vars between tests: `stubEnv` is not undone by
`unstubAllGlobals`, so a SIM_TIMEOUT_SECONDS set for one test configured
every test after it.

…-body

`runtimeCanProxy` treated any release between 22 and 24 as capable, so on
Node 23 — which reached end of life before the backport — a configured proxy
was ignored and the CLI stayed silent about it, which is the exact failure
the warning exists to report. The table is now the two lines that shipped the
support, and anything after them.

`AbortSignal.timeout` keeps firing after `fetch` resolves, so a bound that
elapsed while the body was still being read — a large `files get` — escaped
the client's own handling and printed a raw TimeoutError stack. The top-level
handler now names it, which covers the streaming path as well as the JSON
one. A user's own Ctrl-C raises AbortError and is deliberately left alone.

`files get --output-file` streams the body to disk, and `streamToFile`
converted anything the stream threw into a write failure. So a request bound
elapsing mid-download read as `Could not write <path>: ...`, sending the
reader to check permissions and free space for a timeout they can raise, and
hiding the one instruction that resolves it.

The predicate and that instruction now live beside the timeout that raises
them, so the client, the top-level handler and the download path all say the
same thing. The wrapping stays where it is: the staged-download cleanup runs
off that failure, and rethrowing past it would leak the temporary directory.

Zero is how this function says "no bound", so rounding a positive
SIM_TIMEOUT_SECONDS down to zero inverted the request: anything under
0.0005s asked for the shortest possible timeout and got none at all, leaving
a stalled request to hang. Introduced by the rounding that fixed the
fractional-millisecond rejection.

Floored at 1ms for every positive value; only a literal 0 still disables.