fix(request-executor): serialize every request option in toJSON

[aborovsky]

Follow-up to #769, addressing #769 (comment).

Problem

Request.toJSON() omitted timeout, maxContentSize, decompress, keepAlive and encoding. transformScript rebuilds the request from that projection, so every script-transformed request was reconstructed from a lossy copy.

Round-tripping a request through toJSON() before this change:

field	before	after round-trip
timeout	1234	undefined
maxContentSize	99	undefined
keepAlive	true	undefined
decompress	false	true
encoding	'base64'	undefined (fixed in #769)

Impact, in order of severity:

• timeout and maxContentSize are reachable and were genuinely lost. RepeaterServerRequestEvent carries both from the Bright server and ServerRepeaterLauncher spreads the event straight into new Request({ ...event }). After a script transform they were undefined, so applyCurlTimeout silently fell back to the executor-level timeout and the response cap fell back to maxContentLength.
• decompress was worse than dropped. The constructor defaults it to true, so omitting it flipped an explicit false. Nothing in the codebase currently sets decompress: false, so this was not reachable in practice.
• keepAlive is unread. Nothing consumes Request.keepAlive; connection reuse is driven entirely by the executor-level reuseConnection. Included for completeness only.

Change

toJSON() now serializes the full option set the constructor accepts, so new Request(request.toJSON()) is a faithful copy.

Because toJSON() now carries encoding, the script payload explicitly overrides it to undefined. The body handed to a script is already decoded, so reporting encoding: 'base64' next to it would describe it incorrectly and mislead any script that inspects options.encoding. This keeps the decoded-view contract intact and leaves the restore logic added in #769 behaving exactly as it does today.

Tests

Four new tests, each verified to fail without the source change:

• toJSON round-trips every option the constructor accepts
• an explicit decompress: false survives instead of defaulting back to true
• a per-request timeout is honoured after a script transform (without the fix the request is unbounded and the slow response arrives successfully)
• the script receives timeout / maxContentSize / decompress but no encoding

src/ suite: 264 passed across 24 suites. src/RequestExecutor/: 98 passed (94 on next + 4 new). eslint clean.

tsc --noEmit reports one error at HttpRequestExecutor.spec.ts:158; it is pre-existing on next and untouched by this branch (the only hunk here starts at line 1495).

E2E and smoke suites were not run — they require live Bright API credentials.