fix: probe only read-idle WebSockets

[linkdata]

Summary

• probe a WebSocket only after its read has remained pending for WebSocketPingInterval; local parsing and delivery do not count toward the interval
• keep a socket reader active during each probe so incoming data remains deliverable while the ping awaits its pong
• bound each outbound WebSocket write with requestTimeout, preventing a blocked write from wedging the outbound queue and Request loop

The pre-release lib/wire API now requires positive durations: ReadLoop accepts the idle interval and ping timeout, WriteLoop accepts the write timeout, and PingLoop is removed.

Tests

• added real-WebSocket regressions for a responsive client during slow local processing and for a non-reading client that backpressures the outbound path
• added deterministic wire tests for idle and ping-timeout boundaries, activity during a probe, and per-write timeout renewal and enforcement
• go generate ./...
• go vet ./...
• gofmt -l .
• gofumpt -l .
• staticcheck ./...
• golangci-lint run
• gosec ./...
• JAWS_REQUIRE_NODE=1 go test -race -coverprofile=coverage.out ./... (99.8% overall; lib/wire 100%)
• JAWS_REQUIRE_NODE=1 go test ./...
• go build -v ./...

Closes #354