fix(rpc): add read, write and idle configurable timeouts to gateway

[parthshah1]

Related Issues

Old PR https://github.com/filecoin-project/lotus/pull/13283/files.
Adding configurable read, write and idle timeouts in gateway handler. Fixes this bug.

Proposed Changes

Adding additional timeouts for gateway rpc handler.
Mainly these are the constants (Subject to change):
readHeaderTimeout = 10 * time.Second
readTimeout = 60 * time.Second
writeTimeout = 0
idleTimeout = 60 * time.Second
maxHeaderBytes = 1 << 20

Additional Info

Related slack discussion: https://filecoinproject.slack.com/archives/C05P37R9KQD/p1756354215245379

Checklist

Before you mark the PR ready for review, please make sure that:

• Commits have a clear commit message.
• PR title conforms with contribution conventions
• Update CHANGELOG.md or signal that this change does not need it per contribution conventions
• New features have usage guidelines and / or documentation updates in
  • Lotus Documentation
  • Discussion Tutorials
• Tests exist for new functionality or change in behavior
• CI is green

[parthshah1]

Note: Need a sensible write timeout. 10s maybe.

[BigLep]

I think we'll want a changelog item here.

[parthshah1]

I think we'll want a changelog item here.

Done.

[Copilot]

Pull Request Overview

This PR adds configurable HTTP timeouts to the gateway RPC handler to fix a security vulnerability. The changes introduce five new timeout parameters (read header, read, write, idle timeouts and max header bytes) that can be configured via command-line flags.

• Adds five new timeout constants and corresponding configuration options
• Implements CLI flags for configuring the timeout values
• Updates the CHANGELOG to document the fix

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
gateway/node.go	Adds timeout constants, struct fields, and configuration options for HTTP timeouts
cmd/lotus-gateway/main.go	Implements CLI flags for the new timeout configurations
CHANGELOG.md	Documents the security fix in the changelog

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[Copilot]

The CLI flag is missing the --read-header-timeout option that corresponds to the ReadHeaderTimeout constant. This timeout is configurable in the code but not exposed via CLI, creating an inconsistency in the configuration interface.

Suggested change

	&cli.DurationFlag{
	&cli.DurationFlag{
	Name: "read-header-timeout",
	Usage: "Amount of time allowed to read request headers. Use 0 to disable",
	Value: gateway.ReadHeaderTimeout,
	},
	&cli.DurationFlag{