Minor SignalClient improvements

[hiroshihorie]

• Send pingReq requests
• Use state lock

[ilo-nanpa]

it seems like you haven't added any nanpa changeset files to this PR.

if this pull request includes changes to code, make sure to add a changeset, by writing a file to .nanpa/<unique-name>.kdl:

minor type="added" "Introduce frobnication algorithm"

refer to the manpage for more information.

[Copilot]

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (2)

Sources/LiveKit/Support/AsyncTimer.swift:90

• The startIfStopped() method was removed; please ensure that replacing its usage with restart() elsewhere maintains the intended behavior, as the conditional start logic might differ.

func startIfStopped() { ... }

Sources/LiveKit/Core/SignalClient.swift:639

• Replacing startIfStopped() with restart() for the ping timeout timer may change the timer's behavior; confirm that restart() correctly handles cases where the timer should only start if stopped.

_pingTimeoutTimer.restart()

[ladvoc]

LGTM ✅