fix: silence WebSocket disconnect logs

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Summary

• treat ordinary peer-reachability failures as client disconnects
• cancel the Request without preserving or logging the socket error by default
• keep local oversized-message read-limit failures actionable and logged without Debug
• retain other transport causes and pass them to Jaws.Log when Jaws.Debug is enabled
• document oversized-message cancellation and reporting across root, wire, UI, and the checked-in jaws skill
• cover graceful closes, GoingAway, empty close frames, abrupt EOF, policy/size closes, and a real oversized inbound message
• update the pinned Staticcheck release candidate for Go 1.27 compatibility after CI's stable toolchain advanced

Testing

• GOTOOLCHAIN=go1.27.0 go generate ./...
• gofmt -l .
• GOTOOLCHAIN=go1.27.0 go vet ./...
• GOTOOLCHAIN=go1.27.0 go build ./...
• Staticcheck 2026.2rc1 under Go 1.27
• golangci-lint run
• gosec ./...
• skill-creator/scripts/quick_validate.py .agents/skills/jaws
• GOTOOLCHAIN=go1.27.0 JAWS_REQUIRE_NODE=1 go test -race ./...
• GOTOOLCHAIN=go1.27.0 JAWS_REQUIRE_NODE=1 go test ./...