fix(ui): support promoted JSON fields in JsVar

[linkdata]

Summary

• update github.com/linkdata/jq to v0.5.0 for encoding/json-compatible promoted-field traversal and tagged-unexported endpoint handling
• cover promoted value and pointer reads and writes, root assignment, ClientCheck staging and rollback, ambiguous and ignored fields, removed Go-type-name paths, nil traversal, and shared-name request-loop fan-out
• document the complete generic field namespace, unexported embedding, checker visibility, and nil lookup behavior

Testing

• go generate ./...
• go vet ./...
• gofmt -l .
• staticcheck ./...
• golangci-lint run
• gosec v2.26.1 ./...
• go build ./...
• JAWS_REQUIRE_NODE=1 go test -race ./...
• JAWS_REQUIRE_NODE=1 go test ./...
• 386 test binaries compile for lib/bind and lib/ui; execution remains for CI on this arm64 host

Fixes #367